It appears from that demographic map, there were sizeable populations of Greeks and Armenians pre-genocide, like the tweet says.
----------------------------------
Some perspective.
Obviously there were large Greek and Christian populations
present, since they created that culture/society.
* The area was initially a Greek colony around 600 BC.
* Then it became a Roman Province w/the rise of their Empire.
* W/the fall of Rome around 500 AD, it became Byzantium.
* Over the next 10 centuries it was the Eastern Roman Empire.
* Then around 1450 the Ottomans emerged as warriors of Islam.
By 1914, Ottoman leadership as well as that nation/state was in
an advanced state of emotional decline, leading to the criminal
decision by Sultan Mehmed V to exterminate the Armenians.
Their paranoid argument was that the Armenian Christians had
conspired w/the Russian Orthodox Clergy and Military to
overthrow the Ottomans.
The legacy of Muslim rule is one of death and destruction!