Internal flights. As you know, I love to travel by land and, if you add to this the fact that in these countries internal flights are carried out with very old Russian planes, you understand that I do not recommend using them, especially in Tajikistan and Kyrgyzstan. In Uzbeksitan I took one to reach the north of the country but I had previously checked the statistics of Uzbekistan Airlines and in fact it was not that bad (despite being a propeller plane).
The borders
There are countless border posts between the different countries of Central Asia: some are super scenic and are located on mountain passes, others on rivers and lakes. Some are always open, some are open only in summer (eg Karkara between Kyrgyzstan and Kazakhstan), others closed for years (eg Penjikent, between Uzbekistan and Tajikistan, which would be the most convenient for reaching Dushanbe from Samarkand) and others. they are not international border posts (only the locals of the 2 interested countries can pass). Therefore, when making your travel itinerary, first check that the border post you are interested in is open! Normally the locals can tell you which border posts are open, but you can check on the Caravanistan website.
Personally I had no problems crossing the various borders, often they didn't even check my luggage and they never asked me for bribes (but I saw some people give them). The only country where they do more thorough checks and more applications is Uzbekistan, both inbound and outbound. At the border leaving the country, they even asked me to unlock my phone and show him the photos in my gallery. An invasion of privacy like never before! Apart from that I have always taken a short time and I have not had any hitches. Of course it also depends on the border post; the Uzbek-Kyrgyz border post of Dosyk in the Fargana Valley, for example, is often subject to political tensions and the controls are very thorough. Some people told me it took 4h to cross the border!
Health insurance is required
In Central Asia our health coverage is not valid. My advice is to always take a classic medical-luggage insurance that can cover you during the trip. I am very happy with many insurance companies, a site that compares the policies of different companies and proposes the most convenient policy for that particular trip. To do this you will have to enter the data relating to your trip (country, duration, etc.) and they will send you an email with the best proposal that you can then buy directly online.
