Two

As soon as I heard of the news that the lion bank was back and it would practically keep two headquarters, I couldn't stop thinking of the Roman Empire.

Alas, I mean its splitting into the Western Roman and the Byzantine Empire.

There were many reasons triggering the division (internal power struggle, defense against barbarians, civil wars, taxation and administration convenience), but all could be boiled down to a single root: The empire was too big.

To put it simply, that's because a single administrative center could not receive critical information soon enough to allow timely decisions. (In fact, that's not only the problem of Romans. The Han [漢] Empire at around that same time had its capital at Chang'an [長安] and a "second capital" at Luoyang [洛陽]. The Mongol Empire several hundred years later actually had to split itself into no fewer than five independent kingdoms.)

The problem is, when an empire has grown big enough to need more than one capital, it would usually see its decline very soon.

After all, despite the advances in traffic and communication technology, human beings still influence the others with flesh-and-blood.