Evidently, at some point in Babylonia there was a special way of talking that showed that a person was of good lineage. From what I understand, there is such a thing in England (I’m not so good at identifying English accents). But alas, people can fake their accents, so we cannot use this anymore. I can totally imagine this kind of statement being made in reference to England.
This source presents the tension between Torah learning and lineage. The Torah learning in Eretz Yisrael is good enough such that Ze’iri moved there from Babylonia. But the lineage is not good enough, even for him to marry R. Yohanan’s daughter. R. Yohanan points out to him that there remain in Babylonia both fit Jews (priests, Levites and Israelites) and there remain there unfit classes (mamzerim and netinim). So marrying only those of Babylonian descent will not help.
But R. Yohanan forgot that which R. Elazar taught. Ezra sorted out the genealogical lines before he left Babylonia. Therefore, Ze’iri did not fear marrying one from Eretz Yisrael. Sort of ironic that R. Yohanan forgets that which another Eretz Yisraeli sage teaches.
More stories about lineage.
R. Yehudah does not seem to want to marry off his son because he cannot determine the lineage of the women around him. Ulla begins to point out that we too do not know our lineage. Perhaps we are descended from the Babylonians who raped Israelite women during the time when the First Temple was destroyed. R. Yehuda could respond that he holds that the offspring of a non-Jew and a Jewish woman is fit. Therefore, maybe we are pure.
In this colorful exchange, R. Abbahu ends up interpreting the verse about those taken captive as referring to people who act licentiously, committing adultery. Perhaps, Ulla says, we are descended from such people whose children are mamzerim.
In short, Ulla questions how R. Yehudah can be so sure about his lineage.
Ulla gives him a simple test—those who are less quarrelsome, they are of superior lineage.
Genealogical exams are done by people’s silence, their agreeableness. This is how Rav examined the people of Shafei Halah (Rashi explains that they are vinegar strainers). If they do not argue a lot, then they have good lineage.
If people or families quarrel then one must be unfit and God will providentially prevent them from marrying one another.
One might read these sources as teaching that when people get along it is a sign that they are fit to get married. At the end of the day, this is not bad advice.
This section begins to outline the genealogical purity of the Babylonia—which regions are pure and which are not.
The metaphor here is related to lineage. Babylonia has healthy lineage. The other areas around it—not so much. Mishon is dead, Medea is sick and Elam is dying and almost certainly will die.
The amoraim here delineate the boundaries of Babylonia when it comes to genealogy. Inside Babylonia people are presumed to be genealogically fit. Babylonia lies between the Tigris and the Euphrates. The amoraim discuss how far north and how far south the presumption of genealogical purity extends.
We can see at the end of this description how important genealogical purity was to these people. People who won’t marry into each other’s families did not end up even lending fire to one another, and fire is not something that costs anything to lend.
Rav, Shmuel and R. Yohanan discuss how far Babylonia extends on the upper reaches of the Euphrates.
Abaye curses either Rav or both Rav and Shmuel for extending the border to far north. Note that Abaye wants to limit the extension of genealogical purity so far north. He is more stringent than the other rabbis.