Original sentence: <--The 19th century is 1800s--> In 100 years there were only 200 horses left in the deserts.Later, in the 19th century, Germans brought in thousands of horses and mules.Other researchers have suggested that the horses' ancestors were part of the South African cavalry, possibly horses that escaped, frightened by shots fired from a low flying German airplane during World War I.The Dutch brought them to the Cape of Good Hope in the 17th century.The Namib desert horse is not native to Africa.The horses developed into a distinctive breed with the addition of German bloodlines.There are several theories on how the Namib Desert Horse originated: One is that they are descendents of the horses of the German Schutztruppe.This was during the World War I
Edited sentence: Additional research suggests that at least some of these horses' forebears were part of the South African cavalry which had set up camp in the Namib where some horses escaped, frightened by shots fired from a low flying German airplane during World War I.Horses are not native to Sub-Saharan Africa.It is thought the horses developed into a distinctive breed with the addition of German bloodlines.Other sources suggest they came from imports in the 20th century, between 1904 and the beginning of World War I, when the Germans brought 30,000  horses into the area.Regardless of origins, after 100 years there were only 200 horses left in the deserts, but those that survived had adapted to the conditions of the South Namib Desert.There are several theories on how the Namib Desert Horse originated:  The first horses in sub-Saharan Africa were brought by the Dutch to the area of the Cape of Good Hope in the 17th century.There is also a theory that Namib Desert Horses are descendents of the horses of the German Schutztruppe brought in during the 19th century