Assyria (Heb: Asshur) was a nation and empire in the Middle East. It was north of Babylonia.
It was founded in the 25th century BC by (quite possibly) Asshur son of Shem and grandson of Noah. It started as just a city named Asshur, which began gaining wealth from trading among surrounding nations. Years later, the Akkadian empire took control of the area. After the Akkadian empire collapsed, the Assyrian empire began to rise. This Assyrian empire is the subject of many prophecies in the Bible, including the fall of Israel.
Early History and Foundation
The early formations of the Assyrian Empire began with the establishment of city named Ashur (or Asshur), eponymous to its founder Ashur.
The Bible mentions the nation of Assyria itself first in Genesis, where it says Nimrod went to the land of Assyria and built Nineveh, Rehoboth Ir, Calah and Resen . The plain in which these cities were built would one day be a part of the area over which Assyria would have control.
Under Ashur-dan III
Main article: Jonah (Prophet)
There was a Jewish prophet named Jonah, who God told to go to Nineveh (which was very wicked at the time) and preach a message of repentance to them . Jonah knew that God would forgive them and didn't want that to happen to such a wicked people . So Jonah boarded a ship headed for Tarshish . God sent a storm upon the ship ; and after casting lots, Jonah was found responsible for the storm . Jonah said that if he were to be tossed overboard, the sea would be calmed . The sailors didn't like the idea of tossing overboard one of their passengers, so they tried sending the ship back to shore, but the storm got worse . So the sailors decided to go with Jonah's idea. They asked God to not hold them responsible for killing him, then tossed Jonah over. The sea calmed when they did.  Jonah was sinking so God provided a great fish to swallow him and keep him alive . After 3 days of praying, God commanded the fish to vomit up Jonah onto land . Then God instructed Jonah to go to Nineveh and preach to them . Jonah obeyed this time. Nineveh was so large that it took Jonah 3 days to preach to everyone there.  Nineveh had walls that were 8 miles long, surrounding an area of 1,700 acres. The people repented , but Jonah was not pleased . They were very willing to do this because of recent events. The Assyrian kingdom was at a low point. Assyria suffered military reverses, diplomacy setbacks, famine and domestic uprisings. Also, an eclipse had occurred on June 15, 763 BC. This could have been seen as a terrible omen. Then Jonah shows up with his message from God. God decided not destroy them , but chose such an opportunity to teach Jonah a lesson of mercy and compassion . This happened during the reign of Ashur-dan III.
Under Tiglath-Pileser III
Assyria is mentioned next in Second Kings, where Tiglath-Pileser III (called "Pul") invaded Israel, and received 1000 talents of silver (38 tons). The king of Israel, Menahem, was wicked, so it appears that Assyria was used by God to punish him and Israel for sinning against God .
Again, Tiglath-Pileser came to Israel and took Ijon, Abel Beth Maacah, Janoah, Kedesh, Hazor, Gilead and Galilee, including all the land of Naphtali; he deported their people to Assyria. This was during the reign of Pekah king of Israel .
Another time, Aram was attacking Israel. Ahaz, the king of Israel at the time, requested help from Tiglath-Pileser and said that he (Ahaz) is his (Tiglath-Pileser) servant and vassal. Tiglath-Pileser did help, after Ahaz sent him a gift of all the silver and gold in the Temple of the LORD and the palace treasury.
Later, when another king ascended the throne of Israel named Hoshea, Shalmaneser V king of Assyria came to Israel to attack Hoshea. The reason he did this was that Hoshea was Shalmaneser's vassal and paid him tribute, but Hoshea stopped paying him this tribute. Hoshea was captured and put in prison for this by Shalmaneser. The king of Assyria invaded the whole land and laid siege to Samaria, the capital of Israel, for 3 years. The Assyrians captured Samaria and sent the Israelites to Assyria.
This happened because of Israel's sin against God. They were sent into exile because they rebelled against their Foundation: the LORD. This did not come without warning, many prophets warned Israel this would happen unless they would repent. Israel, being a stiff-necked people, refused to listen to God's prophets. And then this disaster fell on them. The king of Assyria filled the empty cities of Israel with people from Babylon, Cuthah, Avva, Hamath and Sepharvaim. They did not worship the LORD, and were attacked by lions. One of the priests of God was sent to teach them to worship the LORD and be spared. They worshiped the LORD along with their own false gods.
Under Sargon II
Isaiah prophesied about Assyria, saying God would send them against Israel for Israel's rejection of God. This was fulfilled in 701 BC during the reign of King Sargon II of Assyria. Isaiah says that Sargon attacked and captured Ashdod, which is a city in Israel. Isaiah prophesied against Egypt and Cush, after Assyria captured Ashdod. God tells Isaiah to live naked and barefoot. After three years of living like this, God says that just as Isaiah has lived stripped and barefoot for three years, as a sign against Egypt and Cush, so will the king of Assyria lead away his Egyptian and Cushite captives and exiles buttocks bared. Josiah, king of Judah, attacked the king of Assyria when Necho the king of Egypt went to help the king of Assyria. Josiah died in battle.
When Hezekiah (c. 740-686 BC?) became king of Judah, he rebelled against the king of Assyria and didn't serve him . In his 4th year reigning (c. 711 BC?), Assyria had taken Samaria (see the previous paragraph for details). 10 years later, Sennacherib, the new king of Assyria, attacked all of the fortified cities of Judah and captured them.  Hezekiah confessed to the king of Assyria that he did wrong, and asked him to withdraw. Hezekiah promised to pay whatever he demanded of him. Sennacherib demanded three hundred talents of silver and thirty talents of gold from Hezekiah, which he did pay as he said.
Sennacherib sent his supreme commander, his chief officer and his field commander with a large army to Hezekiah who was at Jerusalem. When they came to Jerusalem and stopped at an aqueduct they called for the king; and Eliakim son of Hilkiah the palace administrator, Shebna the secretary, and Joah son of Asaph the recorder went out to them. The field commander asked told them to tell Hezekiah what the king of Assyria had to say to him. The king of Assyria asked on what he was basing his confidence on (which was God). He told him that Hezekiah only spoke empty words when he spoke of his counsel and his might for war . The king of Assyria thought and said that Hezekiah was depending on Egypt, calling Egypt a splintered reed of a staff, which pierces the hand of anyone who leans on it . He also thought that Hezekiah removed the altars and high places of their God and said so if they were to tell him that they were depending on God (actually, Hezekiah brought down the high places and altars of false gods, not Yahweh's ) . Then he said to them to make a bargain with the king of Assyria, he would give them 2000 horses . Then he asked how they could repulse even one of the least soldiers, even though they were depending on Egypt for chariots and horsemen . Then he said that the LORD had told him to destroy Judah .
Eliakim, Shebna and Joah didn't want him to speak in Hebrew and discourage the soldiers, but in Aramaic . The field commander replied asking if it was only to Hezekiah that the king of Assyria wanted to be told what he had spoken . Then he said in Hebrew not to let Hezekiah deceive them, for he could not deliver them from his hand. He said not to let Hezekiah persuade them to trust the LORD. He told them not to listen to Hezekiah and promised prosperity if they make peace with the king of Assyria. He told them not to listen to Hezekiah because he was misleading them when he tells them that the LORD will deliver them. Then he goes on saying that no other god has delivered their land from him. If they couldn't how could Yahweh? The people remained silent because Hezekiah told them not to answer him . Eliakim, Shebna and Joah then went to Hezekiah and told him about what the field commander said with their clothes torn as a sign of mourning and grief . Hezekiah went to the temple in the same manor that Eliakim, Shebna and Joah had come to him . He sent Eliakim, Shebna and Joah to Isaiah the prophet . They filled him in on the day's events and hoped that the LORD would rebuke the field commander . Isaiah told Hezekiah not to be afraid of the words of the king of Assyria . Isaiah prophesied that when the King of Assyria hears a certain report, God would make him want to return to his country . When king of Assyria left Lachish, the field commander withdrew from Jerusalem and found his king fighting against Libnah .
Sennacherib, king of Assyria, received a report that Tirhakah, the king of Cush, was marching out to him to attack him. So Sennacherib sent Hezekiah a message that basically said Hezekiah's God wasn't strong enough to deliver Jerusalem from Sennacherib, like the rest of the gods of the other nations he conquered.  Hezekiah spread out the letter before God, and asked God to take notice . God spoke against Assyria and said that He would force them to leave, and a sign for Hezekiah would be that his people for two years wouldn't have to sow crops, only collect the fruit of the crops. The third year they would have to plant again. God then said that the king of Assyria wouldn't attack Jerusalem, but go home.  That night the angel of the LORD came and killed 185,000 soldiers in the Assyrian camp . They broke camp in the morning and withdrew. Sennacherib went to Nineveh (the capital of Assyria). One day, he was worshiping in the temple of his god (Nisrok) when his sons Adrammelech and Sharezer killed him and escaped to the land of Ararat. Esarhaddon son of Sennacherib then took the throne. Also, Hezekiah is mentioned in the Assyrians' records. God said through Isaiah that lately Assyria was oppressing Israel , referring to what was going on with Hezekiah and Assyria.
Isaiah, prophesying against Tyre, mentioned Assyria. Isaiah said that Assyria had turned the land of the Babylonians into a wasteland, and Tyre would end up like that land too. King Sennacherib had indeed destroyed Babylon, this happened in 689 BC.
After Judah went into exile for 70 years and was released by Cyrus king of Persia, the Jews worked on rebuilding the temple . During the time of rebuilding, Esarhaddon king of Assyria assisted them. It is recorded in Ezra that during the Passover they were filled with joy for the LORD changed the attitude of Esarhaddon so he would assist them in rebuilding the temple.
At the end of the reign of Sin-shar-ishkun (612 BC), Babylon (along with other nations who allied themselves with Babylon) conquered Nineveh and captured it. King Sin-shar-ishkun had died fighting; and the city fell as many Israelite prophets had prophesied, mainly the prophet Nahum. Isaiah, another prophet, also prophesied the destruction of the Assyrian Empire. Assyria was used by God to punish Israel, but the Assyrians were proud and boastful. Isaiah said that God would punish the king of Assyria for the willful pride of his heart and the haughty look in his eyes. He said, later, God would shatter Assyria with His voice and with His rod He will strike them down . In the next chapter the prophet said that Assyria will fall, but no human's sword will make this happen. He was suggesting that God would cause Assyria's fall.
Jeremiah later compared Israel to a scattered flock that lions have chased away. He said that Assyria was the first to devour them. The last to crush their bones was Nebuchadnezzar, king of Babylon. Then he said that God said He would punish the king of Babylon as He had punished the king of Assyria (God punished the king of Assyria at the fall of Nineveh).
Isaiah says that God will gather His people a second time from the nations, including from Assyria. Also, there will be a highway for the remnant (Context says remnant of God's people from Assyria and other nations, could be of Israel or Christians) to travel on from Assyria, like there was for the Israelites when they came from Egypt. Isaiah prophesied that God would remove the yoke of Assyria from Israel's neck. Later, Isaiah prophesied that there will exist a highway from Egypt to Assyria, and the Egyptians and Assyrians will worship together. They, with Israel, will be a blessing on the earth. God will say that Egypt who is His people, Assyria who is His handiwork, and Israel who is His inheritance are blessed . This may suggest that Assyria may one day become a nation again, like Israel became a nation again.
Jeremiah tells the Jews that what was happening to them (the attacks from Babylon) was their fault and they should own up to it. He asked why they should go to Egypt and drink from the Nile or go to Assyria and drink from the Euphrates . Then he says a bit later on in the same chapter that they would be disappointed by Egypt like they were by Assyria .
Jeremiah says in his other book, the Book of Lamentations, that they submitted to Egypt and Assyria so they could get enough bread.