The Hellenes' colonial expansion - initially to western Asia Minor and subsequently into the Black Sea and the western Mediterranean - brought them into touch with populations speaking different languages from their own. Relations with these national groups were peaceful, until Ionia was occupied, first by the Lydians and then by the Persians. The Ionian Revolt at the very beginning of the 5th century gave the Persians a motive for invading Hellas. Their defeat at Marathon in 490 B.C. was followed by a crucial decade. In 480 B.C. the Persians occupied Athens, but their defeat at Salamis in that same year and at Plataea in 479 B.C. put an end to their expansionary military operations in the West.