Answer:
1. primary source materials.
2. historiography
Explanation:
I’m not sure this is the answer you’re looking for but!
• They create decimal system based on Hindu numerals and the zero
• Advances also made in geometry, algebra, and trigonometry.
• Astronomers built observations and measured the Earth. They also used the astrolabe, an instrument designed to measure the plot and position of stars.
There is very little interest in aiding today's Native Americans and certainly one is not giving them back their lands. There are 605 tribes among the Native Americans and most of them work daily to bring to the nations non-Native Americans up to speed about the continuing conditions of Native American reservation regarding schools and daily health care.
<span>Most recently Native Americans have brought the continuing use of Native American sports mascots to be changed. Specifically, changing the name of the NFL's Washington DC football team.</span>
Chemical weapons
Both sides developed lethal forms of chemical welfare that resulted to death of thousands in the trench war.Germany was the first to employ chemical weapons and it is estimated that over 10,000 tonnes of chemical gas, lethal and poisonous was blown.
Trade along the Silk Roads and the trans-Saharan trade routes resulted in "<span>(4) cultural diffusion between different societies" among many other things. </span>
