The origination of Hunan chicken comes from, you guessed it right, the western Hunan area of China. This dish is similar in flavor to Szechuan but tends to be slightly spicier because of the use of dry chilis in combination with the Sambal Oleke.
When I traveled to China, I was deeply impressed by how distinct each region was when it came to their food. I never even realized but, within China there is a wild mix of cross-cultural cuisines. For example, I tried a middle eastern influenced Chinese western cuisine.
Adjust the heat of this dish as you desire. The addition of the dry red chiles is completely optional, but I highly suggest you do so to make this dish as authentic as possible.