Proofs are brought that all 10 categories of people were brought from Babylonia to Israel in Ezra’s time. One who calls someone pasul is himself pasul. Shmuel understands that he is projecting. Rav Yehuda took Shmuel literally and in a long and entertaining story, he declares someone a slave because he called others a slave. He is summoned to Rav Nachman’s court and forced to explain his poisition. But all throughout, Rav Yehuda maintains the upper position and in doing so causes many others to be declared as having flawed lineage in the town of Rav Nachman. Other statements are brought in the gemara stressing the importance of marrying appropriate people.