Complex sentence: Supporters of the mangana and piales events argue that catching horses by their legs has been and is a legitimate method of animal husbandry and therefore part of a celebration of traditional ranching methods of Mexico.
Split into simpler sentences: Supporters of the mangana and piales events argue that catching horses by their legs has been and is a legitimate method of animal husbandry. Therefore, it is properly part of a celebration of traditional ranching methods of Mexico.