Mos Pelgo, most recently seen in the Book of Boba Fett, formerly the beginning location for Season 2 of the Mandalorian introduced us to Marshal Cobb Vanth.
But, did you know that Mos Pelgo actually entered into Legends Canon in 2016 with the Knights of the Eternal Empire?

Mos Pelgo is mentioned in the game Codex, which you can earn the lore from through completing the Uprising: Done and Dusted.

Within the codex entry, it tells the tale of the Dust Viper’s, a gang of miscreants over Tatooine looking to take control by staking territory and moisture farms in the power vacuum left behind after the collapse of the Zakuulan Empire. It is explained that the Dust Viper’s biggest hit was the small town of Mos Pelgo, prior to the Outlander arriving and taking the Dust Vipers down.

Mos Pelgo itself was first introduced, alongside Cobb Vanth, in the Aftermath Novel by Chuck Wendig.

Sources:
Knights of the Fallen Empire – Uprising: Done and Dusted
Codex Entry: Alliance Intelligence Report: The Dust Vipers