The Betsimisaraka constitute the second largest (14.9 percent) group of Madagascar's population and clearly are the most numerous on the east coast. They are divided into three subgroups: the northern Betsimisaraka, the Betanimena, and the southern Betsimisaraka. Their territory extends along the coast in a narrow band from the Bemarivo River in the north to the Mananjary River in the south, a distance of some 640 kilometers. The Betsimisaraka, whose name means "numerous and inseparable," have traditionally been traders, seafarers, and fishers, as well as cultivators of the tropical lowland areas. They trace their origins to the confederacy established by Ratsimilaho, allegedly the son of a British pirate and a Malagasy princess, who unified several small coastal states in the eighteenth century. The confederation continued after Ratsimilaho died in 1751, but it was much weakened by internal conflict and external pressure. The Betsimisaraka territory has included the important port city of Toamasina, as well as Fenerive and Maroansetra at the head of the Baie d'Antongil.

South of the Betsimisaraka are ethnic groups who trace their origins to Islamic traders of mixed Arab, African, and MalayoIndonesian origin who settled on the coasts after the fourteenth century, and are known as Antalaotra ("people of the sea"). The Antambahoaka, whose name is translated as "the people," make up 0.4 percent of the population and live around the Mananjary River just south of the Betsimisaraka territory. They claim as their ancestor Raminia, a king who came from Mecca around the early fourteenth century, and are part of a larger group known as the Zafi-Raminia, or "descendants of Raminia " some of this group migrated from the Mananjary region to become rulers of peoples to the south. Some scholars have speculated that the Zafi-Raminia may have formed part of the ruling class of the Merina, who came to dominate Madagascar in the nineteenth century. Their power and prestige derived from their willingness to use their knowledge of astrology, medicine, and divination to serve the courts of kings throughout Madagascar.

Another people descended from the Antalaotra, the Antaimoro ("people of the shore") constitute 3.4 percent of the population and also live south of the Betsimisaraka. The Antaimoro were apparently the last significant arrivals, appearing around the end of the fifteenth century, possibly from the Arabian Peninsula with a sojourn in Ethiopia or Somalia, just before the coming of the Europeans in the sixteenth century. They are the only Malagasy people before the nineteenth century to possess a system of writing, based on Arabic script. Their books, the sorabe (from the Arabic sura, meaning "writing," and the Malagasy be, meaning "big" or "great"), which were inscribed in ink on special paper made from beaten wood bark, dealt with astrology, divination, medicine, and historical chronicles. Like the Antambahoaka, the Antaimoro are noted throughout Madagascar for their knowledge of the supernatural and medicine.

Among a number of other groups around F879 Farafangana, at the southern end of the Canal des Pangalanes, the most important are the Antaifasy ("people of the sands"), who constitute 1.2 percent of the population. To the south, the Antaisaka (5.3 percent of the population) are found in large numbers around the alluvial valley of the Mananara River. The Antanosy ("people of the island"), who live in the extreme southeastern part of the island around Faradofay, make up 2.3 percent of the population.

The peoples of the eastern escarpment separating the east coast from the central highlands are the Sihanaka ("people of the lake"), who represent 2.4 percent of the population the Bezanozano (0.8 percent), living south of the Sihanaka and the Tanala (3.8 percent). The Sihanaka live around Lake Alaotra and practice wet-rice cultivation in a manner similar to that of the Merina. The Bezanozano ("many little braids," referring to their hair style), the Tanala ("people of the forest"), and the inland Betsimisaraka practice slash-and-burn agriculture in the forests, cultivating dry rice, corn, yams, and other crops. Although the Merina conquered the Sihanaka, the Bezanozano, and the inland Betsimisaraka in the early nineteenth century, the southern Tanala remained independent up to the French occupation.

Data as of August 1994