They had pre-mined themselves. I think the genesis (1st) block reward was 5,500,000 MNX which is mentioned in whitepaper. And I must say this is poorly planned.
I thouk pre-mined blocks corresponded to the adress which mined between July 20-26. But apparently you are right, this is the only pre-mined block specified in the whitepaper, so
I don't know what to think about the blocks mined between July 20-26 ...Poor planning or cheating.