Complex sentence: Conclusive dates for the site's occupation have not been determined; one survey concluded that occupation began around 1200 CE and continued until at least 1400, while a study of the site's pottery held that it was inhabited from approximately 1350 until 1541.
Split into simpler sentences: Conclusive dates for the site's occupation have not been determined; one survey concluded that occupation began around 1200 CE and continued until at least 1400. A study of the site's pottery held that the location was inhabited from approximately 1350 until 1541.