They made Channels underground a lined with clay to prevent sepage in the surrounding soil. They were a big contribution and we still do something inspired by that today.
Concerning this era, there are several themes which we learn in the American Indian literature. Among these we have the Indian ceremonial chants and oratory, the influence of christianity, ethnicity and racism.
1 mm = 0.0001m
450 x 0.001 m = 0.45 meters
<span>The Monroe Doctrine prohibited European powers from interfering in Latin American affairs. 1824</span>
The correct answer is 3) a polytheistic mythology
Hope this helps