When and where were the southern two tribes of Judah and Benjamin taken into captivity?

Les explains that the ten tribes of the southern kingdom were taken into captivity into Syria about 775 B.C. and never really came back as tribes, which is why some call them the lost tribes. Then about 150 years later, the southern two tribes of Judah and Benjamin—which we call Judah—were taken captive all the way to Babylon, and only a few thousand came back after the 70 years. The rest were assimilated into the whole Middle East, similar to how immigrant groups in America eventually lose their mother tongue over two or three generations.