Have you seen evidence that Gautama Buddha visited Shambhala?

While preparing the huge online-conference "Life of the Most Worthy" on the topic of the life of the Buddha, we came across information that Gautama Buddha, in his spiritual aspirations, was looking for contact with Shambhala. And also that in the end his search was crowned with success and he was accepted by the Bodhisattvas of Shambhala. However, no documentary evidence of this has yet been found. Have you met ancient sources in any language of the world that speak of this? Maybe you know what direction to look for?