Maria Martinez and her husband, Julian Martinez, were a formidable team. Maria was an expert potter and could burnish clay to a brilliant shine. Julian was an astute designer who painted the pots with a matte slip using designs adapted from rock art and ancient pottery fragments. Together they developed a firing technique that resulted in these distinctive black-on-black ceramics. This jar was purchased at the 1939-1940 Golden Gate International Exposition held on San Francisco's Treasure Island. Maria and Julian Martinez traveled to the fair to hold pottery-making demonstrations and to sell their art at the Indian Market, organized by the Covelo Indian Community of the Round Valley Reservation in Mendocino County. The stylized tree motif that appears on this jar is said to have been inspired by California's soaring pines and redwoods. After Julian’s death in 1943, Maria continued her work with other family members. Their legacy is part of a continuous pottery-making tradition in San Ildefonso Pueblo that involves the collaboration of men and women.