Complex sentence: They continued through Texas's time as part of Mexico, when more Europeans, especially Americans arrived, to the subsequent declaration of independence with the Republic of Texas, and did not end until 30 years after Texas joined the United States.
Split into simpler sentences: They continued through Texas's time as part of Mexico, when more Europeans, especially Americans arrived, to the subsequent declaration of independence by the Republic of Texas. The conflicts did not end until 30 years after Texas joined the United States.