In the 18th century, the Isaaq Sultanate, a Somali successor state to the Adal Sultanate, was established by Sultan Guled Abdi at Toon. The sultanate spanned parts of the Horn of Africa and covered most of modern-day Somaliland, as well as being its pre-colonial predecessor. The sultanate had a robust economy and trade was significant at its main port of Berbera and the smaller port town of Bulhar, as well as eastwards at the frankincense-exporting port towns of Heis, Karin, and El-Darad.