This old map clearly shows the original border. From 1777 to 1801 it was the border between Spain and France, from 1804 to 1809 it was France-Haiti, from 1809 to 1821 it was Spain-Haiti, from Dec 1821 to Feb 1822 it was Spanish Haiti-Haiti, from 1844 to 1861 it was DR-Haiti, from 1861 to 1865 it was Spain-Haiti, and from 1865 to 1929 it was DR-Haiti. In 1929 and later in the 1930s 5,000 km2 were ceded to Haiti because Haiti claimed that land and in order to successfully appropriate itself of this Dominican territory, the Haitian government encouraged its peasant population to move into the Guava Valley (today Centre Plateau) and become subsistence farmers. It was the presence of these Haitians that the Haitian government used to justify its claims of one of the most fertile valleys on the island, even though now its not as fertile as it once was.
Before 1495 the island had several borders due to the five Taino kingdoms, from 1492 to 1697 there was no border due to islandwide Spanish rule, from 1697 to 1777 there was a border slightly different from the one in the map, and then in 1777 the border that followed the extent of the territory occupied by the Spanish and the French was established.
http://img.photobucket.com/albums/v223/Liz-ONBC/On Stranger Tides/Haiti/HaitiMapcopy.jpg
Before 1495 the island had several borders due to the five Taino kingdoms, from 1492 to 1697 there was no border due to islandwide Spanish rule, from 1697 to 1777 there was a border slightly different from the one in the map, and then in 1777 the border that followed the extent of the territory occupied by the Spanish and the French was established.
http://img.photobucket.com/albums/v223/Liz-ONBC/On Stranger Tides/Haiti/HaitiMapcopy.jpg