How many years did the black death take to kill 25 million people

In the 1330s, many natural disasters and plagues led to widespread famine, starting in 1331, with a deadly plague arriving soon after. Epidemics that may have included the plague killed an estimated 25 million Chinese and other Asians during the fifteen years before it reached Constantinople in 1347.

the answer to your question is a. the salt plains

in 1811, he led an expedition, known as the george c. sibley expedition, to improve relations with the pawnee and kansa tribes, and also to locate the rumored jefferson's salt mountain