The Peloponnesian League was an alliance of ancient Greek city-states, dominated by Sparta and centred on the Peloponnese, which lasted from c.550 to 366 BC. It is known mainly for being one of the two rivals in the Peloponnesian War (431–404 BC), against the Delian League, which was dominated by Athens. Name The Peloponnesian League is the modern name given to the Spartan system of alliances, but it is inaccurate because there were members outside the Peloponnese, and it was not really a league. The ancient name of the League was "the Lacedemonians and their allies". This is misleading as well, because Sparta could have allies outside of the Peloponnesian League. History Foundation (c. 550 BC) In its early history, Sparta expanded by conquering Laconia and Messenia and reducing their population into slavery (as helots), but the subjugation of Tegea on its northern border failed at the battle of the Fetters. Following this defeat, Sparta abandoned its military conquests and adopted a diplomatic strategy, known as the "bones policy", by appropriating the relics of mythical heroes worshipped in the Peloponnese, starting with Orestes, the son of Agamemnon, whose bones were transferred from Tegea to Sparta. This new diplomacy was likely sponsored by Chilon, ephor c.556, who therefore enabled Sparta to present itself as the natural successor of the mythical Achaean kingdom of Agamemnon as described by Homer. Tegea then signed an alliance treaty with Sparta, which became the starting point of the subsequent Peloponnesian League. Tegea was pushed towards Sparta by its fear of Argos, its eastern neighbour. For the same reason, all the other neighbours of Argos rapidly concluded treaties with Sparta on the Tegean model: Mantinea, Phlieus, Corinth, Epidaurus and the other cities of Argolis. They were followed by Elis, the large city of the western Peloponnesus, and all the Arcadian communities of central Peloponnesus. By 540s, Sparta had concluded alliances with all the Peloponnesian cities, apart from Argos and Achaean cities on the northern shore. There was no collective treaty between all the members of the League. As hegemon (leader of the League), Sparta concluded a separate treaty with each member, which therefore entered the League upon its conclusion. Each member swore the same oath with Sparta: "to have the same friends and enemies as the Spartans, and to follow them withersoever they may lead". League members were consequently not bound together, only to Sparta, and could