The Lord had taken Israel out of Egypt in the most spectacular way, sustaining them in the wilderness in a most caring way, and prospered them in the Land of Canaan just as He had promised, but they refused to obey Him. Therefore, of the northern ten tribes, the Bible says,

Now it came to pass in the fourth year of King Hezekiah, which was the seventh year of Hoshea the son of Elah, king of Israel, that Shalmaneser king of Assyria came up against Samaria and besieged it. And at the end of three years they took it. In the sixth year of Hezekiah, that is, the ninth year of Hoshea king of Israel, Samaria was taken. Then the king of Assyria carried Israel away captive to Assyria, and put them in Halah and by the Habor, the River of Gozan, and in the cities of the Medes, because they did not obey the voice of the Lord their God, but transgressed His covenant and all that Moses the servant of the Lord had commanded; and they would neither hear nor do them (2 Kings 18:9–12).

There were times of righteousness, but toward the end those times disappeared, and wickedness engulfed the nation. Therefore, the Lord had to do what He had promised to do in the Law of Moses.

The Assyrians were known for their brutality and cruelty, and Israel suffered through the violent ways of the Assyrians, all because Israel refused to heed the Lord.