From his early research, Sahagún wrote the text known as "Primeros Memoriales." This served as the basis for his subsequent, larger "Historia General". He conducted his research at Tepeapulco, approximately 50 miles northeast of Mexico City, near present-day Hidalgo. There he spent two years interviewing approximately a dozen village elders in Nahuatl, assisted by native graduates of the college at Tlatelolco. Sahagún questioned the elders about the religious rituals and calendar, family, economic and political customs, and natural history. He interviewed them individually and in groups, and was thus able to evaluate the reliability of the information shared with him. His assistants spoke three languages (Nahuatl, Latin and Spanish). They participated in research and documentation, translation and interpretation, and they also painted illustrations. He published their names, described their work, and gave them credit. The pictures in the "Primeros Memoriales" convey a blend of indigenous and European artistic elements and influences. Analysis of Sahagún's research activities in this earlier period indicates that he was developing and evaluating his own methods for gathering and verifying this information.