Based on ethnographic research in Egypt and the United States, this chapter will focus on the emergence and dynamics of transnational networks of modern Arabian horse breeding with a focus on the Straight Egyptian Arabian horse as a nationalized and trademarked modern sub-breed. Following a practice-oriented social anthropological approach and drawing on insights from both science and technology studies and human-animal studies, I argue that a central feature of the Arabian horse industry and global breeding community is genealogical talk about the Arabian horse. Ancestral knowledge about the most precious bloodlines and the ability to trace a horse’s genealogy and pedigree to its “pure” Arab Bedouin origin in the deserts of Arabia, the Levant, and Egypt’s royal stables, is a matter of ongoing debate. This chapter will discuss issues of modern breed formation and the performative employment of the Arabic concept of purity and authenticity (Arabic āṣāla/āṣīl) by modern Arabian horse breeders in relation to two case studies: the infamous but extremely popular story of the stallion Nassralla, born in 1954 in Egypt at the Egyptian state-stud al-Zahraa and accused of impurity and tainted blood; and the exclusion of desert-bred Tahawi-bloodlines from the World Arabian Horse Organization (WAHO) in 1972. Taken together, I suggest, these two instances of exclusion based on bloodlines suggest how the breeding of modern Egyptian Arabian horses implies a submerged politics of structural violence against traditional Arab society.