The city of Gerrha was taken by the Qarmatians at the end of the ninth century. It was from the Persian Gulf near present-day Hofuf. The researcher Abdulkhaliq Al Janbi argued in his book that Gerrha was most likely the ancient city of Hajar, located in modern-day Al-Ahsa, Saudi Arabia. Al-Janbi's theory is the most widely accepted one by modern scholars, although there are some difficulties with this argument, given that Al-Ahsa is 60 km inland and thus less likely to be the starting point for a trader's route, making a location within the archipelago of islands comprising the modern Kingdom of Bahrain, particularly the main island of Bahrain itself, another possibility.