It is worth mentioning a form of dialectical monism in the ancient Aztec philosophy and especially in the concept of ” Teotl “, which is at the center of Aztec metaphysics and cosmology. Teotl is the expression of an endless alternation of continuous and cyclical oscillation between opposite poles. Teotl is thus characterized by a dual prominent structure, which results from the union of opposites , themselves characterized by complementarity. The dual pairs involved include : the masculine and the feminine, dark and light, order and disorder, hot and cold, life and death, being and non-being etc. The interdependence and higher union of the principles of life and death in Teotl, for example, was represented by Aztec artists of Tlatilco and Oaxaca in masks where one half is alive while the other half died, revealing the skull bones.
Reference: James Maffie, Aztec Philosophy, Internet Encyclopedia of Philosophy
Related notions: Dialectical monism in Heraclitus