Final answer:
Trade on the Silk Road led to cultural and goods exchange, while trade across the Sahara resulted in wildlife extinction and the rise of new settlements to support trade activities.
Step-by-step explanation:
One difference in the demographic effects of trade between the Silk Road and the trade across the Sahara desert between ca. 1200 and ca. 1450 CE is related to the impact on wildlife and settlement patterns. On the Silk Road, trade facilitated the spread of various goods and cultural exchanges without a significant reported impact on wildlife extinction or the creation of new settlements specifically for trade purposes.
Conversely, in the Sahara, the increased demand for goods like ivory led to the hunting of large animals to extinction in North Africa. Moreover, the trade in the Sahara led to the emergence of several new settlements such as Sijilmasa, Ghat, and Kano, formed to support the movement of goods across the desert.
Merchants and nomads in the Sahara heavily relied on these settlements as exchange points, where goods were traded and caravans replenished, distinctively shaping the demographic patterns in the region.