The interest of the British Government of India in Afghanistan in the nineteenth century came about in order to

During the nineteenth century, the British Government of India's interest in Afghanistan was primarily driven by the 'Great Game'—a strategic rivalry with the Russian Empire [2]. The British were haunted by the fear of a Russian invasion of India through the north-west frontier [3]. Consequently, Afghanistan was viewed as a crucial geographical buffer state [3]. British policy aimed to establish a permanent barrier against Russian expansion and ensure that the Russian empire did not gain influence over Kabul. This geopolitical anxiety led to the First and Second Anglo-Afghan Wars, as Britain sought to control Afghan foreign affairs to protect its Indian dominion [3]. While commercial interests in Central Asia were a secondary factor, the overarching objective was to prevent Russian encroachment and secure the frontiers of British India [3].

Sources

1. [2] Modern India ,Bipin Chandra, History class XII (NCERT 1982 ed.)[Old NCERT] > Chapter 10: India And Her Neighbours > Relations with Afghanistan > p. 174
2. [1] Modern India ,Bipin Chandra, History class XII (NCERT 1982 ed.)[Old NCERT] > Chapter 10: India And Her Neighbours > Relations with Afghanistan > p. 176
3. [3] Rajiv Ahir. A Brief History of Modern India (2019 ed.). SPECTRUM. > Chapter 5: Expansion and Consolidation of British Power in India > First Anglo-Afghan War (1839-1842) > p. 130