Purpose: This paper aims to examine the sixteenth-century Nahua society of central Mexico to answer the question, what commercial ethical norms operated in the sixteenth-century Nahua society? After decades of trying, Western business models and managerial theories have not met expectations in terms of fostering a socially and environmentally sustainable future. Qualitatively different approaches are needed, and one way to find them is to look at business models, norms and practices that operated in societies that were isolated from Western influences. Design/methodology/approach: This paper contributes to efforts to find and analyze historical texts that include business practices. In particular, this study uses grounded theory techniques to examine the presence of ethical commercial norms in one of history’s foundational ethnographic texts, The Florentine Codex, a sixteenth-century study of Nahua society. Findings: This study identified six commercial ethical norms that structured Nahua commerce: “care for others,” “exercise prudence,” “tell the truth,” “be respectful of others,” “show reverence to the gods” and “be humble.” Confidence in these findings was enhanced by their “qualitative degrees of freedom,” whereby these norms were found to operate in other sectors of Nahua society. Originality/value: This study contributes to the literature by demonstrating ethical norms of commerce that can emerge in isolation from Western cultures; providing a rigorous and novel methodology for deriving norms from historical texts; and expanding knowledge of business practices beyond modern Western contexts.