Eleven of the sons of Jacob/Israel and the two sons of Joseph became the 13 tribes of Israel. Often the tribes are misnamed the 12 tribes instead of 13. Two reasons may be: 1. The Levites were not given land because they were not to farm the land but to work in the temple so the land was divided up twelve ways. 2. Rev 7:4-8 says: “And I heard the number of them which were sealed: and there were sealed an hundred and forty and four thousand of all the tribes of the children of Israel.  Of the tribe of Juda were sealed twelve thousand (1). Of the tribe of Reuben were sealed twelve thousand (2). Of the tribe of Gad were sealed twelve thousand (3).  Of the tribe of Aser were sealed twelve thousand (4). Of the tribe of Nepthalim were sealed twelve thousand (5). Of the tribe of Manasses were sealed twelve thousand (6).  Of the tribe of Simeon were sealed twelve thousand (7). Of the tribe of Levi were sealed twelve thousand (8). Of the tribe of Issachar were sealed twelve thousand (9).  Of the tribe of Zabulon were sealed twelve thousand (10). Of the tribe of Joseph were sealed twelve thousand (11). Of the tribe of Benjamin were sealed twelve thousand (12).” That listed 12 tribes