Arzawa was a region and a political entity (a "kingdom" or a federation of local powers) in Western Anatolia in the second half of the 2nd millennium BC (roughly from the late 15th century BC until the beginning of the 12th century BC). The core of Arzawa is believed to be along the Kaystros River (now known as Küçük Menderes River), with its capital at Apasa, later known as Ephesus. When the Hittites conquered Arzawa, it was divided into three Hittite provinces: a southern province called Mira along the Maeander River, which would later become known as Caria; a northern province called the Seha River Land, along the Gediz River, which would later become known as Lydia; and an eastern province called Hapalla.