Y Wladfa (Welsh pronunciation: [ə ˈwladva], "The Colony"), also occasionally Y Wladychfa Gymreig (Welsh pronunciation: [ə wlaˈdəχva ɡəmˈreiɡ], "The Welsh Settlement"), refers to the establishment of settlements by Welsh immigrants in Patagonia, beginning in 1865, mainly along the coast of the lower Chubut Valley. In 1881, the area became part of the Chubut National Territory of Argentina which, in 1955, became Chubut Province.In the 19th and early 20th century the Argentine government encouraged emigration from Europe to populate Patagonia which, until the Conquest of the Desert began in the 1870s, was terra nullius, claimed but not controlled by Argentina until 1884.

Between 1856 and 1875, 34 settlements of immigrants of various nationalities were established in Santa Fe and Entre Ríos. In addition to the main colony in Chubut, a smaller colony was set up in Santa Fe by 44 Welsh people who left Chubut, and another group settled at Coronel Suárez in southern Buenos Aires Province.The Welsh-Argentine community is centred on Gaiman, Trelew, and Trevelin. Chubut estimates the number of Patagonian Welsh speakers to be about 1,500, while other estimates put the number at 5,000.