BEIJING: China, Tanzania and Zambia signed an initial agreement on a railway project aimed at improving the rail-sea intermodal transportation network in East Africa, Chinese state media said on Wednesday (Sep 4). President Xi Jinping witnessed the signing of the memorandum of understanding on a Tan...
If it's similar to most of the other BRI projects, Tanzania and Zambia get railways, Chinese workers get jobs, more expertise in the field, and China gets access to healthier/wealthier markets in the two countries.
Money. From people buying Chinese stuff. >80 million people live in those countries and they would like very much if they started buying lots of cars and electronics