Physically the sahuagin do not differ by region, but there are some cultural differences. Sahuagin who live in the Underdark or on the archipelago have more interaction with other races than those who live in the ocean, especially the deep ocean. Ocean-dwelling sahuagin rarely learn languages other than their own and Underseacommon, a trade language used by undersea races.
The language of the sahuagin comes from the same root language as that spoken by the shaahesk. A sahuagin can understand about 10% of what a shaahesk is saying and vice versa. All sahuagin speak the same language but there are regional dialects; for example, the sahuagin who live in the deep ocean incorporate gill movements and even bubbles emitted from their gills as non-verbal cues in their communication.
The sahuagin do not have a unified government. In the Underdark the sahuagin live in tribes led by a chieftan or a shaman, and relations with other tribes range from friendly to openly hostile. Sahuagin in the ocean are ruled by a military dictator similar to the Voivode of the shaahesk, and are focused on subjugating the other undersea races for control of the seas. Sahuagin on the archipelago pay homage to this dictator but have their own government.