Between 1851 and 1856 , he traversed the continent from west to east , discovering the great waterways of the upper Zambezi River .
In 1849 , Livingstone crossed the Kalahari Desert from south to north and reached Lake Ngami .
Between 1851 and 1856 , Livingstone traversed the continent from west to east , discovering the great waterways of the upper Zambezi River .
In 1849 , Livingstone crossed the Kalahari Desert from south to north and reached Lake Ngami .