Wonderwoman was from Themyscira as well as the island being home of the Amazons.
The Greek Gods were at war with the Titans. Hippolyta was seduced by Hades and tricked into opening the gates for the invading Titans. After the bloody war, Zeus banished Hades to Tartarus, and commanded Hippolyta to watch over the door to Tartarus on the god's chosen city-state of Themyscira. At some point after arriving on the island and assuming the role of Queen she longed for a child of her own and as such sculpted Diana out of clay. The sculpture was then brought to life by the gods.
The island had been hidden from the rest of the world until that child, Diana, came out to help "Man's World" on messages sent by J'onn J'onzz against the Imperium. The one strict rule on the island is that no man is ever allowed to set foot on Themyscira.
When Felix Faust attacked Themyscira turning everyone into stone statues, Wonder Woman used the help of the Justice League to defeat Felix Faust and his benefactor Hades. With the help of the League Hades was returned to Tarturus. Hippolyta thanked the League but upheld the law, banishing her daughter Diana from Themyscira for bringing men to the island.
Some time later, Faust's spirit, possessing the Annihilator armor crafted by Hephaestus, returned to Themyscira and stormed the gates of Tartarus and deposed Hades, causing an imbalance in the supernatural order. The Amazons were hard pressed to keep the various demons from escaping from Tartarus. Diana, who was tasked by the gods to stop Faust, and Hawkgirl arrived to assist and managed to restore Hades to the throne of Tartarus. Hippolyta then decided to lift her daughter's exile and appointed her as Themyscira's ambassador to the outside world.