Upvote:-1
Eastern civilizations are older and already had some widespread organized religions like Buddhism and Hinduism when Christianity reached them back thousands of years ago. So Christianity didn't penetrate the East well since there was already a strong belief in something else there.
The West was either conquered(The Roman Empire imposed Christianity on all its residents) or settled(The Americas) by Christians.
Upvote:2
Christianity reached China by 400 AD. By the time of Genghis Khan, there was a thriving Christian community. Some of the royal princesses and a leading general were Christian. However, a series of calamities struck the Roman empire, weakening the center and crippling missionary activities for centuries. For example, Kublai Khan sent to Rome a request for 100 Christian scholars to teach his people Christianity, but only one showed up. (The offer was made to several religions, like Buddhists, Muslims, etc.)
The calamities included a colder climate leading to famine, the plagues of Justinian and the later Black Death, invasions from Germany, Asia, spread of Islam, etc. These geopolitical changes (plus geographic limitations) thwarted the eastward and southern expansion until the time of the explorers. The strength of Islam prevented European ships from sailing on the Indian ocean or eastern mediterranean, so they had to round the cape of Africa and go west to the Americas to pursue trade. This lead to Christianity being spread westward to the Americas.