In terms of creation myths, I believe they share the same ones as the better known Mexica as they are both Nahua peoples.

For the city and civilization itself, the Tlaxcalans were a people that founded their city after driving out the previous peoples known as the Chimichecas.

Tlaxcala is known for being one of the few states in a constant state of war with the Mexica in wars knows as "guerras flóridas" never to be conquered. They also sided with the Spanish during their conquest of Mexico.