On 12 October 1492, after several months at sea, Christopher Columbus arrived on the coast of the OTL Wakayama Prefecture, in Japan.
The single rather large POD in this history, is the lack of the Americas, leaving Europe and Africa directly across the AtlantoPacific from Eastern Asia. Rather than the predictions of Eratosthenes and Ptolemy, it was the predictions such as that of Martin Von Behaim in his 1492 Erdapfel (the oldest surviving globe), which was followed by Columbus on his fateful voyage, which proved to be correct. In OTL this roughly means eliminating both American continents and their associated islands, including Greenland and moving 20 degrees west to 160 degrees west.
Although believing himself to be in India, Columbus was quickly corrected by the Japanese and early trade relations were established between the far eastern cultures and those of medieval Europe.
The first group to traverse the merger of the Atlantic and Pacific was Polynesian sailors from Tahiti, who landed in OTL Angola and set up some Moai along the coast, but settled for no longer than a few decades.
A few hundred years later the Vikings went the other direction, led by Erik the Red, who landed in Kamchatka and made a small settlement, although this minor settlement would last a few centuries before being abandoned in 1320 due to bad conditions and a lack of contact with Scandinavia and Iceland.
Columbus’ 2nd voyage took him to China and the Philippines. After trading at the Chinese port of Fuzhou, but with little success, he sailed down the Philippines coast, establishing trading bases, including Fernandina at OTL Lopez Bay, at Isabella OTL San Miguel Bay, Antigua at OTL San Pablo Bay and Saint Kitts at OTL Lianga Bay.
His 3rd voyage took him to the East indies and to Papua New Guinea. He established Spanish claims at Sorong, named San Salvador in Papua New Guinea, and a trading base named Santa Maria in Ternate.
As the area to the west was better explored and charted, the great sea that divided Europe and East Asia was named the Ocean Sea, after the mythical river that surrounded all the lands of the Earth.
Initial timeline of early European discoveries and interactions 1495 - 1516