Why could Marco Polo travel the world unhindered?

There are two versions of why Marco Polo could move freely around the world.
According to the first assumption, young Marco was taken on the journey by his father and uncle, the Venetian merchants. So he was lucky enough to cross most of the world by sea and land and reach China.
The second version says that Marco Polo was in the service of the Mongol Khan Kublai, who later became the Chinese emperor. Carrying out his secret assignments, Marco Polo and traveled the world.