Why do you say that Gansu is a big man in the northwest?

Geographical location and weather reasons. Gansu province belongs to the northwest of China, with a relatively large sandstorm and a relatively dry climate. People living in Gansu province will have dark red skin and look like big men, so when it comes to Gansu, they are big men in the northwest. Lanzhou, the capital of Gansu Province, governs 12 prefecture-level cities and 2 autonomous prefectures with a total area of 425,800 square kilometers.