Sparta was an important Greek city-state in the Peloponnesus. It was unusual in that it had a diarchial system, with two kings ruling at the same time. The kings were called "Arkhagêtai". They were hereditary rulers, and came from two separate dynasties. According to tradition, the two lines, the Agiads and Eurypontids, were descended from the twins Eurysthenes and Procles. These twins were said to be the descendants of Heracles, who conquered Sparta two generations after the Trojan War. The dynasties were named after the twins' grandsons, the kings Agis I and Eurypon. The "Agiad" line was regarded as being senior to the "Eurypontid" line.