As has been noted already, liturgies weren't technically added in the 4th Century.
There were many, many liturgies/masses throughout Christendom in the first 3 centuries. Each one of them connected back to the earliest liturgies amongst the Apostles & their followers, and all had close similarities, but local differences.
The Liturgy of St. Basil took the local liturgy and added to it, such as some anaphora prayers and other prayers. The Liturgy of St. John Chrysostom took this, and added to it, and removed a bit. He actually shortened the Liturgy, making it a bit more manageable for use in Constantinople.
As for other liturgies, they just come out of older local traditions. All are quite similar when you look at them and their structure, because they all come out of the earliest liturgies. Eventually the West unified all the various rites in it's borders under the rite practiced in Rome, this was done more through direct enforcement and intervention. The East (minus the non-Chalcedonians) unified all under the rite practiced in Constantinople, this was done through a little less direct enforcement, and largely occurred due to the missionary work by Constantinople and it's heavy influence over Antioch, Jerusalem & Alexandria. Over time, in the East, monasticism also played a huge part in adding to the Liturgy. So if you go to a monastery, say, on Mt. Athos, the Orthros (morning) and Liturgy services will be very, very long. Some hymns/psalms are sung only in part outside of monasteries. Also, even though we all share the same liturgy, that of St. John Chrysostom, there have still been individual developments in each region. In Greece, you'll find different hymns in some portions than you'll find in Russia. There will be other minor differences too, like when they open & close the Royal Doors, how they make processions, where they stand when reading the Epistle/Gospel etc...