So Ben-jamin was the other tribe besides Judah that was not lost? Would they have been people like the Samarians and Galileans in the new temple era? IOW, was Jesus raised around Benjamin-ites, or was he fully of and surrounded by Judah-ites?
A little-remembered passage from 2 Chronicles 11 says: 13 The priests and Levites from all their districts throughout Israel sided with him. 14 The Levites even abandoned their pasturelands and property, and came to Judah and Jerusalem because Jeroboam and his sons had rejected them as priests of the LORD . 15 And he appointed his own priests for the high places and for the goat and calf idols he had made. 16 Those from every tribe of Israel who set their hearts on seeking the LORD , the God of Israel, followed the Levites to Jerusalem to offer sacrifices to the LORD , the God of their fathers. 17 They strengthened the kingdom of Judah and supported Rehoboam son of Solomon three years, walking in the ways of David and Solomon during this time.
As you can see there were no tribal bloodlines lost from any of the 12 tribes.
What was lost were those actual people who were scattered whereever the Assyrians sent them....perhaps some eventually to Afghan and Pakistan. This article lists some of the facts supporting that thesis.
So....the dispersed tribes were lost, and we shouldn't be absolutely astounded to find different "jewish" customs among some of the other nations in those regions.
However...the bloodlines were not lost, and in that sense there were no lost tribes.