In reply to neilwiltshire:
irans got good climbing but access is hard in late winter. the caspian region can get a lot of snow and its not a priority to keeps many mountain roads cleared.
that said, if youre the frontier type, the region - inclluding the south side of the caucusus has lots of winter routes, but needs the right preparation. local mountain guiding groups would be very happy to see foreign climbers. costs and hospitality are never prohibitive in the region, tho visas may be.
otherwise, china.
north of the yunnan snow shed (ie north of kangding) conditions are stable and loads of <6000m stuff. all much less commercial than the sub-con, lat-am, europe, but also well accessed, good food, genuine mountains.
if either appeal pm me, can help you sort it.