Board Thread:Show-Related Questions/@comment-173.44.55.206-20170304204724/@comment-27794543-20170307110435

It's unlikely that there were any 'clans' when Becca arrived on Earth – just random groups of survivors. With her, Becca brought vials of Nightblood serum and told the survivors that she's here to help. Given her scientific knowledge, as well as, providing the 'cure', the ground survivors may have seen her as their hero. From this, the legend of Bekka Pramheda was born.

The title "Commander" came from the patch on Becca's spacesuit (which was later used to make the Flamekeeper's kit). For all we know, Becca never used the title (she didn't speak Trigedasleng, so she definitely didn't use "Pramheda"). The title may have come years later when the Grounders decided they needed a term for the carrier of A.L.I.E. 2.0. and settled on using the word on her patch.

Through the years, language changed and facts were forgotten. Becca, a woman of science, became Bekka Pramheda, a religious figure, perhaps a deity. Her company's corporate logo, "∞", became the Grounder's "most holy symbol". The capital's name, "Polis", derives from "Polaris", Becca's space station / company's name.

As for the clans, it's unknown how they came about. There may have been one clan that spread out and split into many clans. Alternatively, the post-apocalypse survivors may have been widely spread out and later came together to form clans. The common mythology suggest the former. However, Becca's limited supply of the serum (since it has to be made in space, more could not be produced), the rarity of the Nightblood gene, and survivors in other parts of the world (e.g. the Egyptian scavenger seen at the end of "Echoes"), suggest most apocalypse survivors were able to survive without the serum and without Becca.

What is known is that all Nightbloods descent from Becca or one of the people she inoculated (remember the vials she brought to Earth). JR confirmed that Nightblood is passed down genetically, so regardless of what clan a Nightblood is part of, at least one of their ancestors had to be one of the original Natblidas.