The common theme shared by the Maya and Aztec civilizations is that they were both interested in astronomy. Both civilizations developed complex astronomical calendars and systems to track celestial movements, which were integral to their agricultural practices, religious rituals, and overall understanding of the cosmos.
While marriage customs and clan structures were important aspects of their societies, the specific theme of interest in astronomy stands out as a significant shared characteristic. They were not nomadic civilizations; both the Maya and the Aztecs were primarily sedentary, establishing and developing complex city-states and civilizations. Additionally, there is no historical basis for them trading for wives with the Dutch and French, as these European interactions occurred later and under different circumstances.