what was marco polo's transportation when he traveled to china with his father and his uncle?

Lorin, they started from Venice, went to the Mediterranean, crossed the Black Sea and reached
Bagdad. Then they crossed the Strait of Hormuz and went through the desert in Iran and finally reached Pamirs. From there, they went to Kashgar.

At that moment, there was no plane. And they were not rich people. So they should have travelled by ship and on foot.