The 1200s BC is a decade which lasted from 1209 BC to 1200 BC.
Approximate starting date of Late Bronze Age collapse, a period of migration, unrest and destruction in the eastern Mediterranean and Ancient Near East, and beginning of the Iron Age in the Near East.
Theseus, legendary King of Athens, is deposed after a reign of 30 years and succeeded by Menestheus, great-grandson of Erichthonius II of Athens and second cousin of Theseus' father Aegeus. Menestheus is reportedly assisted by Castor and Polydeuces of Sparta, who want to reclaim their sister Helen from her first husband Theseus. Theseus seeks refuge in Skyros, whose King Lycomedes is an old friend and ally. Lycomedes, however, considers his visitor a threat to the throne and proceeds to assassinate him. (Other accounts place these events a decade earlier. See 1210s BC.)