I would engage your question by asking a very loaded questions of my own: "What makes an explorer famous to you?"

I would hazard a guess based on your question, and based on the fact that this is on Reddit that you are of European descent or tradition. In that case you are already predisposed to have studied or heard about European explorers instead of Asian explorers. In school you only have a certain amount of time to spend discussing the ages of exploration so your teachers likely focused on the ones that you would be familiar with or relate to, those of Europe. This is especially true for an American student who is even more removed from the history of the Middle East.

There is also the matter of what we considers an explorer famous, or great, and as humans we naturally favor the greatest, biggest, loudest, people and the events that have the largest impact on history. The discovery, colonization, and settlement of North and South America had a huge impact on North and South America, Europe, and African history. Less so on that of India, China, or the Middle East. As a small matter of geography the Americas are much harder to reach across the Pacific than they are across the Atlantic, so Chinese or Japanese explorers couldn't make that gigantic lasting splash like Spanish and Portuguese could. When compared to repopulating two continents, the exploits of other explorers kind of pales no matter how important they were.

All that said, there are famous explorers from the East, they likely just had a small or nuanced impact on our European based lives. In their home countries they can be named by school children just like we might with Columbus. Ibn Battuta was one of the greatest explorers of the Islamic world of the 12th century. Ahmad ibn Fadlan from the Baghdad Caliphate visited the Vikings in the 10th century. Zheng He and Hong Bao were two of the most famous Chinese explorers who charted courses through the Pacific Islands, around India, and into parts of Africa and the Middle East. The list goes on.