The Pythian Games, honoring Apollo, Leto, and Artemis were held here every eight years. After the Dorian invasion (1100 BC), the Amphictyonic League was formed, consisting of twelve city states each represented equally in the League, regardless of their actual power. When the Kriseans began to extort visiting pilgrims (who usually left from the ports of Krisa), the inhabitants of Delphi complained to the League, who declared war on the Kriseans in what would later be called, the First Sacred War (595-586 BC). After the First Sacred War, Delphi became autonomous and the Kriseaen plain was dedicated to Apollo and made holy. No one was allowed to till the soil or use the the plain for grazing. The Pythian games were also reorganized at this time and were changed to occur every four years, like the Olympics. Delphi gained increasing international prestige and earned the favor of foreign nations such as Lydia and Egypt. In 548 BC, the temple was destoryed by fire, but was rebuilt through an international effort. During the Persian wars, Xerxes attempted to plunder the temple in 480 BC, but as his troops reached the Sanctuary of Athena Pronaia, they were crushed and scattered by large boulders falling from the crags.