Upon its emergence in the early 17th century, the highland kingdom of Imerina was initially a minor power relative to the larger coastal kingdoms and grew even weaker in the early 18th century when King Andriamasinavalona divided it among his four sons. Following almost a century of warring and famine, Imerina was reunited in 1793 by King Andrianampoinimerina (1787–1810). From his initial capital Ambohimanga, and later from the Rova of Antananarivo, this Merina king rapidly expanded his rule over neighboring principalities. His ambition to bring the entire island under his control was largely achieved by his son and successor, King Radama I (1810–28), who was recognized by the British government as King of Madagascar. Radama concluded a treaty in 1817 with the British governor of Mauritius to abolish the lucrative slave trade in return for British military and financial assistance. Artisan missionary envoys from the London Missionary Society began arriving in 1818 and included such key figures as James Cameron, David Jones and David Griffiths, who established schools, transcribed the Malagasy language using the Roman alphabet, translated the Bible, and introduced a variety of new technologies to the island.