Is there any proof that Budai was an actual historical figure

Does any online site refer to evidence that this monk ever existed as an actual historical figure? If the person is believed to be so important and famous as next Buddha then where is the tomb? [Refer to wikipedia](https://simple.m.wikipedia.org/wiki/Budai) > Many Chinese Buddhists believe he was a reincarnation of Maitreya, the person who will become the next Buddha after Gautama Buddha.