During Spanish settlement, the name was Hispanicized to Cosoy.The village was made up of thirty to forty families.

Miguel Costansó described being guided by the Kumeyaay to the village as "they arrived on the banks of a river hemmed in on either bank by a fringe of willows and cottonwoods, very leafy...within a musket-shot from the river they discovered a town or village of the same Indians who were guiding our men.

Within this, they explained, they took refuge against attacks from their enemies.”[3] The Spanish referred to the village as Cosoy, a hispanized name of Kosa'aay.

[1] On July 16, 1769, a Mass was held in the dedication of Mission San Diego de Acalá and El Presidio Real de San Diego, the first mission and presidio in Alta California, and the founding of the settlement of San Diego in Old Town, from which the Kumeyaay village of Kosa'aay was incorporated.

[4] The village is acknowledged through the Iipay Tipai Kumeyaay Mut Niihepok Park at Old Town San Diego State Historic Park, which was developed with the Kumeyaay Diegueño Land Conservancy (KDLC) to enhance visibility of Kumeyaay culture and history in the village's original site.