Who was the first explorer of the old times to actually set foot Asia?

The first known explorer to set foot in Asia from the West was Marco Polo, an Italian merchant and traveler, who journeyed through Asia in the late 13th century. However, if considering earlier interactions, the Greek explorer Alexander the great reached parts of Asia during his conquests in the 4th century BCE. Additionally, the Vikings, under figures like Leif Erikson, are believed to have reached parts of North America, but their direct contact with Asia is less documented.