Very schematic from region I live around - Geneva and Aosta are not that far on the map and seem close neighbours, but highest part of alps lies in between, pas

Very schematic from region I live around - Geneva and Aosta are not that far on the map and seem close neighbours, but highest part of alps lies in between, passes can be brutal and far apart (>=2500m high, ie St Bernard pass from where famous dogs come from, can end up snowed anytime all year round and especially 2000 years ago, at least 6 months/year unpassable for carriages and dangerous for anything else).