Who were the people whom the Prophet, peace and blessings be upon him, passed by on his way to Hunayn, and who possessed Dhat Anwat? And why did he not stop and invite them to Tawhid (monotheism)? And was it mentioned that he invited them to that?

In the story of Dhat Anwat, it is not mentioned that the Prophet (peace and blessings be upon him) passed by a tree around which people were performing 'itikaf (devotional retreat). Rather, it was a tree well-known from the days of Jahiliyyah (pre-Islamic ignorance), and the narrations do not mention anyone being present at it when the Prophet (peace and blessings be upon him) passed by. Some narrations of the hadith may even suggest that they did not pass by this specific tree, but rather passed by a large tree that reminded them of it. The Arabs used to visit this tree one day a year. The reprehensible act in this story was not in people actually performing 'itikaf and committing shirk (associating partners with Allah) at this tree, but rather in the statement of one who said, "Make for us a Dhat Anwat," and this is what the Prophet (peace and blessings be upon him) condemned.