An intriguing idea.
"This often led to similar customs" is especially interesting.
Common customs → shared laws → cities → conflicts ( → and, if conditions allowed, empires)
Most imperial expansion occurred across similar agro-ecological zones on the same latitude (Rome, Caliphates, Mongols, Imperial China, Ottomans, Spain, Russia, Habsburgs). The historical exceptions I can think of occurred outside of Eurasia (Inca, Zulu, Mali). (Exception: Japan)
Empires and conflicts spread most easily where nature doesn’t fight them.
When communication became the core of economic activity, we got maritime empires (Britain, USA). (Exception: Athens)
Now, decentralised information exchange is the core. Axes of coordination may form through common time zones, because that’s how digital economies are organising.
This might mean more physical interaction longitudinally, within a time zone, because the growth of a digital economy might pressure the physical economy to reflect it.