I Chronicles 7-9
"So all Israel was enrolled by genealogies ... And Judah was carried away into exile ..." (9:1). Being Jewish in ancient times was mainly a matter of proving one's ancestry. There were certainly converts in the community, but land-owning families could trace their genealogies back to Abraham. Tragically, the Babylonian exile years destroyed some of that continuity. Those who returned to Judah were only given land if they could prove their family line.
The inheritance of faith is much more secure. Through Christ, we enjoy "the riches of His grace, which He lavished upon us" (Eph 1).