There are all sorts of arbitrary lines that can be drawn to demarcate the Earth’s ‘west’ from its ‘east’ – arbitrary because, while our planet rotates counterclockwise around the sun, what constitutes west and east is really a matter of perception. The Greenwich Meridian establishes longitude and separates our western and eastern hemispheres, but it’s just a human construct.

Over the 55 days of cycling from home to Baku, there were various points that felt like a transition of sorts from west to east: riding into Hungary (given the country’s former Eastern Bloc alignment), reaching the Black Sea, and crossing the Bosphorus in Istanbul – the great ‘meeting point of the world’ and the boundary between Europe and Asia. But, in the context of this latest part of my adventure, the Caspian Sea makes a strong claim to be a bigger frontier, and I felt it powerfully as my flight left the Azerbaijan coastline last night and headed out over the darkness of the water bound for Aktau in Kazakhstan.

Perhaps that claim is amplified in my mind because the Caspian is the first proper expanse of water I’ve had to cross by means other than my bicycle since the English Channel some 4,100 miles earlier. In truth, my thinking is shaped too by the fact that it also marks a threshold to a phase of my ride that feels particulalry formidable. There was always a sense about my itinerary that it was split between what was entailed west of the Caspian (a very large logistical puzzle, but riding to a fairly fixed schedule and sleeping in a bed each night) and the undertaking east of it (a less convoluted set of logistics, but the prospect of a much looser schedule). The first eight days across the desert – split roughly evenly between Kazakhstan and Uzbekistan – will involve little civilisation and some nights wild camping.

From the top floor of my hotel, there’s a 360° view of the surrounding cityscape of Aktau. To the west is the Caspian, and to the east an urban sprawl which, once the sun had set and the lights of Aktau sparkled, had a discernible perimeter. Beyond that perimeter lies a vast expanse, and some significant trepidation!