Barbecue probably originated from the way ethnic minorities eat. The Japanese call roast mutton "Genghis Khan Cuisine" (mentioned in Aoki Zheng's China Pickling Recipe), which seems to belong to Mongolians. But when I read The Secret History of the Yuan Dynasty, I didn't see the barbecue.
Genghis Khan certainly eats mutton. The secret history mentioned several times that he went to a place and ate a pair of breast-fed mutton. Lambs are "double breastfed" (fed by two ewes) and must be very fat and tender. One lamb at a time is enough. But it seems to be boiled for nothing. Even if it's roasted, it's roasted whole, unlike the barbecue in Beijing.
If it is a barbecue in Beijing, he is probably impatient and dissatisfied. I have been to Inner Mongolia several times and have never eaten barbecue on the grassland. Therefore, it is doubtful whether this is Mongolian cuisine.
The barbecue stalls in Beijing are all Muslim restaurants. "Barbecue Bay" originally had a small plaque written by Qi Baishi, which clearly read: "Muslim Barbecue Bay". This plaque is written on rice paper and embedded in a frame. The handwriting is very good. Two lines of footnotes were added at the back: "The book has no baking words, so you should ask for death." I once wrote to ask Zhu, a linguist, if there was a word "roast" in ancient times. Sid replied that the word was not in the ancient dictionary. It seems that the word "roast" is a modern man-made word.
Is this how Hui people eat? I have been to Lanzhou, where Hui people are concentrated, and Urumqi, Yili and Turpan in Xinjiang, and I have never seen a barbecue like Beijing barbecue. Kebabs are everywhere, but that's another kind. When the barbecue in Beijing originated and which nationality it belongs to, there is no way to verify it. Anyway, it has taken root and settled down in Beijing, becoming one of the "three barbecues" (barbecue, roast duck and roasted sweet potatoes) in Beijing, and it is the masterpiece of "eating Beijing children".