There are actually quite a few on that may be of interest. In particular post-Soviet Central Asia has seen several books written about national borders, as the concept of national identity is largely a new thing there (it was effectively introduced by the Bolsheviks in the 1920s, and the modern states have only existed independently since 1991). I will note that the books I note here I have not fully read, but am aware of the content and have read snippets at times:

• Border Work: Spatial Lives of the State in Rural Central Asia by Madeleine Reeves (2014). This looks at Kyrgyzstan, Tajikistan, and Uzbekistan, and the troubled borders they share. There's a lot of interplay in this region as well, as ethnic groups from one titular state can live in fair numbers in a different one, which causes friction at times.

• Nationalism in Central Asia: A Biography of the Uzbekistan-Kyrgyzstan Boundary by Nick Megoran (2017). This is slightly different than above in that it only looks at Kyrgyzstan and Uzbekistan, and Megoran is more focused on how the two states have developed as independent states, with a focus on their often-tumultuous relationship. It is worth noting that this book may need some updating as Uzbekistan's long-term president Islam Karimov died in 2015 and his successor Shavkat Mirziyoyev has set out a more moderate policy (though that is a more modern topic than appropriate here).

• On the Edge: Life Along the Russia-China Border by Franck Bille and Caroline Humphrey (2021). This was just released late in 2021 so I haven't read it yet, but I'm looking forward to it. Bille has written before on Russia's Asian border regions, so is familiar with the topic, and he looks at how the Russians and Chinese developed very distinct ways at looking at their long border.

• The Slovak–Polish Border, 1918-1947 by Marcel Jesensky (2014). Switching from a more modern era and one in Asia to something from nearly a century ago in Central Europe. Jesensky is Slovak himself and taught at my alma mater (I actually TAd a class for him in grad school, but spoke to him maybe once). This looks at the complicated issue of interwar Central/Eastern European borders, and how that mess worked out, with a particular focus on Poland and Slovakia.

• Defending the Border: Identity, Religion, and Modernity in the Republic of Georgia by Mathijs Pelkmans (2006). The last one I'll mention, Pelkmans' book looks at Adjara in southwestern Georgia along the Turkish border. The region is distinct compared to the rest of Georgia in that most of the population, while ethnically Georgian, are Muslim, as the area was ruled by the Ottoman for centuries. While the region has traditionally been very intertwined with the Turkish side, and today has a thriving border trade, during the Cold War it was totally closed, which had a major disruption on people's lives. Pelkmans looks at this and how the Adjarans perceive themselves in modern Georgia and how they have re-integrated with Turkey as well.