Huge 1200 Postcard Collection from 1910s

This is a scrapbook full of ~1200 postcards from all over the world. Most of the postcards are at least partially handpainted, many are original photographs, and they are organized by country. From what I could tell, the major countries were Japan, China, Taiwan, Philippines, Vietnam, India, many in the middle east, Turkey, Germany, Italy, France, Switzerland, Denmark, Spain, England, Scotland, US, Canada, Brazil, and various African colonies. There are numerous fascinating postcards such as a Philippian head hunter, decapitations in China, African Tribes, etc. Most have postmarks from 1914-1918, but a few are in the early 1920s-1930s. The collection is from my great-great-grandma, who traveled the world in the 1910s and 1920s. If someone has an idea of what something like this might be worth and how to sell it best, I would love some advice. Thanks!