Ancho chilis are dried Poblano Chili peppers. They originate in the state of Puebla, Mexico. They are made when poblano pepper are allowed to stay on the vine to ripen until they turn red, then harvested and dried. This process effectively preserves the peppers, giving them much longer kitchen life.
Though there is a slight kick to them, they are considered to be of mild heat measuring between 1,000 – 2,000 Scoville Heat Units (SHU) on the Scoville Scale compared to say the chipotle pepper (which are dried jalapeno peppers) which measures on average about 5,000 SHUs. The peppers are known for their rich smoky quality, with sweet to moderate heat and a mild paprika flavor.