Cambodia to the UK
 

In the initial stages of planning this trip,and looking for advice on the general direction to take.

Will more than likely be on Thai registered bikes. 450s or 650s. 1st thoughts were:
Cambodia- Vietnam-Laos..........Europe. The bit in the middle is where i am not sure.

Am i right in thinking China cannot be passed through? I was hoping to hit Nepal Kyrgyztan and Kazagztan.

As i said planning is in very early stages so help route planning greatly appreciated.