Luka was a à ¾upa (administrative division) of the medieval principality of Zahumlje (later Hum) located in parts of Bosnia and Herzegovina, and Croatia. It was situated in a swampy area on both sides of the Neretva river, from the Bregava and the Trebià ¾at, down to the Neretva Delta and Adriatic Sea. It bordered the à ¾upas of Rastok (west), VuÃÂerià(north), Drijeva (east) and the Adriatic Sea (south).