The Spanish came to Mexico in search of spices and spices did they find. Probably all in a Mole Poblano. The dish is from the Puebla state, a UNESCO Heritage site known for Mexican Baroque to Renaissance architecture and Mole Poblano: The Jewel of Puebla.
The dish is a composite of spices, mixed with ground chilli, and spiced with spices. A thickening agent like powdered bread is added to complete this dish.
Mole Poblano is steeped in history and culture of Mexico. This is probably why this dish is in the centre of Mexican culture and history. Some call it the national dish of the country.