The exile came about because of sin: The children of Israel sinned against God, their God, who had delivered them from Egypt and the brutal oppression of Pharaoh king of Egypt. They took up with other gods,
fell in with the ways of life of the pagan nations God had chased off, and went along with whatever their kings did.
They did all kinds of things on the sly, things offensive to their God, then openly and shamelessly built local sex-and-religion shrines at every available site.
They set up their sex-and-religion symbols at practically every crossroads.
Everywhere you looked there was smoke from their pagan offerings to the deities - the identical offerings that had gotten the pagan nations off into exile. They had accumulated a long list of evil actions and God was fed up,
fed up with their persistent worship of gods carved out of deadwood or shaped out of clay, even though God had plainly said, "Don't do this - ever!"
God had taken a stand against Israel and Judah, speaking clearly through countless holy prophets and seers time and time again, "Turn away from your evil way of life. Do what I tell you and have been telling you in The Revelation I gave your ancestors and of which I've kept reminding you ever since through my servants the prophets."
But they wouldn't listen. If anything, they were even more bullheaded than their stubborn ancestors, if that's possible.
They were contemptuous of his instructions, the solemn and holy covenant he had made with their ancestors, and of his repeated reminders and warnings. They lived a "nothing" life and became "nothings" - just like the pagan peoples all around them. They were well-warned: God said, "Don't!" but they did it anyway.
They threw out everything God, their God, had told them, and replaced him with two statue-gods shaped like bull-calves and then a phallic pole for the whore goddess Asherah. They worshiped cosmic forces - sky gods and goddesses - and frequented the sex-and-religion shrines of Baal.
They even sank so low as to offer their own sons and daughters as sacrificial burnt offerings! They indulged in all the black arts of magic and sorcery. In short, they prostituted themselves to every kind of evil available to them. And God had had enough.
God was so thoroughly angry that he got rid of them, got them out of the country for good until only one tribe was left - Judah.
(Judah, actually, wasn't much better, for Judah also failed to keep God's commands, falling into the same way of life that Israel had adopted.)
God rejected everyone connected with Israel, made life hard for them, and permitted anyone with a mind to exploit them to do so. And then this final No as he threw them out of his sight.
Back at the time that God ripped Israel out of their place in the family of David, they had made Jeroboam son of Nebat king. Jeroboam debauched Israel - turned them away from serving God and led them into a life of total sin.
The children of Israel went along with all the sins that Jeroboam did, never murmured so much as a word of protest.
In the end, God spoke a final No to Israel and turned his back on them. He had given them fair warning, and plenty of time, through the preaching of all his servants the prophets. Then he exiled Israel from her land to Assyria. And that's where they are now.