It still is. The Holy Orthodox Christian Church lives on, carrying on the ancient tradition from apostolic times up to today.
As for ignorance, don't feel so band. It seems like western society doesn't want us to know about it. Or else western society thinks so highly of itself, it doesn't consider the 1,000 years of Byzantium worth looking at. Or maybe it's because it's impossible to look at Byzantium without staring CHRIST in the face.
My recollection of high school history is that you learn about ancient (pagan) Greece as a mere setup for Rome. Then when Rome falls, you get a brief mention of the split, but then rather than follow the trail of the eastern empire, it's immediately forgotten, and we skip ahead to Charlemagne, and follow the Roman/Germanic narrative, to the exclusion of the rest of the civilized world.
Meanwhile, Byzantine (Orthodox Christian) culture moved north into slavic lands -- Bulgaria, Ukraine, Russia, Romania, Serbia. The west, if you haven't noticed, seems quite prejudiced against those lands and peoples. They get treated like the white trash of the world by the western nations. But that's OK. I'm sure it will all work out in the end. Forgive me for running on.
Can you suggest a good basic book or website or summary I can use to get me started?