In late September and October 1937 Rafael Trujillo ordered the killing of Haitians in the Dominican border region. Soldiers and police, sometimes with civilian participation, used machetes and rifles over roughly a week, reportedly testing suspected Haitians by asking them to pronounce the Spanish word for parsley, perejil, a shibboleth that gave the episode its name; the bodies of many victims were thrown into the river that marks the frontier. Estimates of the dead range from about 4,000 to 20,000 or more, with figures of 12,000 to 15,000 common in the literature. The killings formed part of a wider policy of 'Dominicanisation' of the frontier that also expelled survivors and restricted Haitian labour and settlement. Under diplomatic pressure mediated by the United States, Cuba and Mexico, the Dominican Republic agreed in January 1938 to pay Haiti an indemnity of 750,000 US dollars, of which about 525,000 was actually paid, without any admission of responsibility or prosecution of those involved. In 2013 a Dominican constitutional court ruling retroactively stripped citizenship from many Dominicans of Haitian descent, an act critics linked to the same policy tradition.
Dominican army and police units under Rafael Trujillo killed Haitians and Haitian-descended residents of the border region and drove survivors into Haiti
The Dominican census of 1935 counted 60,517 'foreign' members of the black population, overwhelmingly Haitians and their descendants, most of them in the border provinces and the sugar bateyes. Death-toll estimates range from about 14,000 to 40,000, with most scholars near 20,000, so the share killed is put at anywhere from a fifth to three-fifths of that community.
Estimates range from about 4,000, based on contemporary consular counts of identified victims, to 20,000 or more in Haitian and later accounts; figures of 12,000 to 15,000 are widely used. The Dominican government suppressed records and disposed of bodies in the rivers, so no count was ever possible, and the number remains an estimate built from refugee testimony and diplomatic reporting.
The killings, the expulsion of survivors and the subsequent exclusion of Haitians from the frontier zone are documented in Haitian and United States diplomatic reporting of 1937-38 and in the historical research summarised by Britannica.
Dominican Rep., Haiti