The Sthaviras gave rise to several schools, one of which was the Theravāda school. Originally, these schisms were caused by disputes over vinaya, and monks following different schools of thought seem to have lived happily together in the same monasteries, but eventually, by about 100 CE if not earlier, schisms were being caused by doctrinal disagreements too.
By the latest at around 100 CE, schisms were being caused by what type of desagreements?
doctrinal