Complex sentence: The Muong and the Tai have had a mutual influence on each other's culture, so today the Muong are ethnically and linguistically close to the Vietnamese, but culturally and socially similar to the Tai.
Split into simpler sentences: The Muong and the Tai have had a mutual influence on each other's culture. So, today the Muong are ethnically and linguistically close to the Vietnamese, but culturally and socially similar to the Tai.