Bananas were brought out of their original territories in India and South East Asia to Asia Minor and then on to Africa, starting about 327 BC. They came to Central and North America by way of explorers and missionaries through the Caribbean, where mass production began in 1834.
Bananas are a good source of several nutrients, such as potassium and magnesium, Vitamins B6 and C, as well as fiber and antioxidants. The pectin found in bananas provides structural form. Test results have suggested that pectins might provide protection against colon cancer.
About 75% of a fresh banana’s weight is water. Dehydrated bananas lose about 96% of this water content, which means that ounce for ounce, they become a far more concentrated source of nutrients, with the exception of Vitamin C (especially sensitive to heat, and water soluble).

More information:
Pectin and pectic-oligosaccharides induce apoptosis in in vitro human colonic adenocarcinoma cells.

Does Dehydrating Destroy the Potassium in Bananas?