Ezra is chronicling the genealogies of the twelve tribes. We're up to our fifth tribe, Manasseh.
Ezra starts with the half tribe of Manasseh that lives east of the Jordan River. It extends to the northern most point of any of the twelve tribes to Mt Hermon (almost to Damascus). And it extends halfway into Gad's territory, cutting a deep u-shape into Gad.
Ezra says they were numerous.
He also comments that they were "mighty men of valor, famous men, heads of their father's households.
Then there is a giant plot twist.
But they acted treacherously against the God of their fathers, and played the harlot after the gods of the people of the land, whom God had destroyed before them.I Chronicles 5:25
So the God of Israel stirred up the King of Assyria and he carried them all away into exile "until this day" (Ezra's day).
This included the tribes of Rueben, Gad and Manasseh.
Manasseh covered only 4 verses; but they packed a punch.
Play stupid games. Win stupid prizes.
You have to wonder if this wasn't a long-coming consequence for asking to stay east of the Jordan. I know they had herds to consider; but God knew that. I'm sure God had a plan for their herds. But having the Jordan between them and their culture and their tabernacle and the others tribes left them vulnerable to outer influence.