It’s kind of complicated, but here’s an abbreviated version.
Historically, the Nativity of the Lord, the Baptism of the Lord, visit of the Magi, and Wedding at Cana were all celebrated on the same day, as the feast of the Manifestation of the Lord. In the West, this was on December 25 and in the East, this was on January 6. This difference was because the West thought Jesus was conceived on April 25 and the East on May 6.
After the first Ecumenical Council in 325, the Church became aware of the different dates. Around 378, the East began to celebrate the Western date for Christmas and kept the Feast of the Baptism (Theophany) on January 6. The West adopted the Eastern celebration of the Baptism and visit of the Magi (Epiphany) on January 6. Over time, the over emphasis on the Magi led to the Western Church creating a separate feast for the Baptism of the Lord.
As a side note, Armenian Christians originally celebrated these feasts as they are celebrated now in Eastern Catholic and Orthodox Churches, but reverted to celebrating all of these feasts on January 6.
Visit the following link from the Melkite Diocese of Newton for more info
melkite (dot) org/uncategorized/god-in-the-flesh-at-bethlehem-and-the-jordan
