Two seasons of archaeological investigations at the Merchant site and its surroundings documented one of the most unusual and significant pre-Hispanic settlements on the southern Great Plains of southeastern New Mexico. It was first excavated over 60 years ago by Robert Leslie and the Lea County Archaeological Society to rescue the site from looters. Through the following decades, it remained a somewhat legendary yet mostly unpublished mystery of southern New Mexico archaeology due to a few incomplete and confusing accounts of contiguous rooms, middens, deep pithouse structures, a distinctive corrugated ceramic ware, and thousands of projectile points. In 2014, the Carlsbad Field Office of the Bureau of Land Management, with funding provided by the Permian Basin Programmatic Agreement, issued a contract to conduct remedial excavations to recover information from looted and exposed features and to stabilize the site. A second season of fieldwork was completed in 2019 to further explore and confirm the intriguing results of the investigations completed in 2016. The Merchant site is a pueblo settlement of at least sixty jacal rooms, kivas, gridded agricultural fields, and exceptionally dense midden and kiva closure deposits containing tens of thousands of bison, antelope, and deer bones. Maize was cultivated in gridded fields near the settlement, but mesquite was also a primary component of the diet. Chemical compositional analysis determined that Ochoa Indented Corrugated ceramic vessels were made and used locally and were rarely transported beyond the settlement, while analysis and ultraviolet fluorescence sourcing of flaked stone tools and debitage found that most raw materials were obtained from distant sources throughout the plains of central Texas and the Panhandle. Analysis of radiocarbon and ceramic thermoluminescence dates place the occupation between A.D. 1300 and 1400. The architecture, gridded fields, and corrugated ceramics of the Merchant site have a seemingly Southwestern appearance and origin. The masses of large mammal bones and thousands of projectile points and hide processing tools made from distant stone material sources reflect Plains-like hunting practices. The appearance of Southwestern traits at a settlement located 150 km beyond what is conventionally thought of as the easternmost boundary of the Southwest is so striking that the immediate and obvious interpretation is some yet to be identified Southwestern community or social group migrated to the southern Plains of New Mexico. Upon reviewing the information compiled from two seasons of excavations and surveys, the migration scenario is not as conclusive as it once seemed. Migration is a tidy and straightforward way to explain the foundational event leading to the settling of the Merchant site in the early-to-mid 1300s; the reality was likely a complex interplay of purposive social actions and economic decisions. The Merchant site can be contrasted with data from Henderson Pueblo and Bloom Mound, two sites in the Roswell Oasis of southeastern New Mexico investigated by John Speth during eight seasons of fieldwork between 1994 and 2009. The cooperative and competitive aspects of long-range hunting expeditions and sedentary settlement identified at the Merchant site and Roswell Oasis present a fascinating case of hybridity and heterogeneity, merging Southwestern and Plains material culture, ceramics, subsistence economies, and architecture into something new and unprecedented on the southern Plains. These developments profoundly altered the historical trajectory of settlement, adaptation, and social arrangements across southeastern New Mexico and west-central Texas during the 14th century.