Given the task definition and input, reply with output. In this task, you are given a question and a context passage. You have to answer the question based on the given passage.

What were they demonstrating against?, Context: Turkey: The torch relay leg in Istanbul, held on April 3, started on Sultanahmet Square and finished in Taksim Square. Uyghurs living in Turkey protested at Chinese treatment of their compatriots living in Xinjiang. Several protesters who tried to disrupt the relay were promptly arrested by the police.

Chinese treatment of their compatriots living in Xinjiang