Captain Haines, a British officer who surveyed Yemen in the 1830s, described Mukalla as a town of 4500 inhabitants with a significant trade in slaves. British explorers Theodore Bent and Mabel Bent used Mukalla several times in the 1890s to enter and exit the Wadi Hadhramaut: “Our starting-point for the interior was Makalla, which is 230 miles from Aden, and is the only spot between Aden and Maskat which has any pretensions to the name of port. The name itself means 'harbour'… Here we were deposited in December 1893 by a chance steamer, one which had been chartered and on which for a consideration we were allowed to take passage. I took turns with the captain to sleep in his cabin, but there was nothing but the deck for the others.” In 1934, British traveler and explorer Freya Stark began her journey into the hinterland of the Hadhramaut from Mukalla, and her stay in that city is recorded in her book, "The Southern Gates of Arabia".