why was it critical for good pioneer trails going west to have a decent route through the Rocky mountains

An educatethe yuan dynasty was responsible for which of the following: i. improving the road system ii. increasing sea trade with india and south east asia. iii. extending the canal system iv. brutal warfare and ruthless killing of people in order to take over china. a. i & iii c. iv only b. ii only d. all of the above member of the government

What championed nationalism and denounced nullification

Why does this website suck for taking all my ranks away for no reason : (