Twenty-one years ago, Western powers led by the US started to engage in Afghanistan militarily and politically to reform the country according to "Westernised" ideals. After the Bonn Agreement, two realities were created: whereas on the one hand Afghan society received aid from third countries which were actively working on the ground, on the other hand, the Taliban formed a parallel structure that matured over the years and eventually ended up regaining control of the country. Whilst one could think that systematic errors were the result of inefficiencies perpetrated over time, they were already present from the beginning and grew larger. In fact, the failure of nation-building started much earlier than the summer of 2021. As for the EU, it has never been the protagonist behind the short-lived democratisation of Afghanistan, but it targeted the country mainly with humanitarian missions. To understand the reasons why these missions were not successful and how they fostered a sequence of miscalculations and mistakes that developed either inside the Union or as a consequence of exogenous hurdles, it is fundamental to learn the social, ethnic, religious, geographical, and political context of Afghanistan.