This paper uses the decade-long collaboration between the Indian paleobotanist Birbal Sahni (1891–1949) and his Chinese doctoral student Hsü Jen (Xu Ren 徐仁, 1910–1992) to offer a connected history of mid-twentieth century scientific activity in China and India. Possibly the first Chinese scientist to earn a PhD from an Indian university (Lucknow, 1946), Hsü was certainly the first to be appointed to a faculty position in India. Sahni and Hsü's attempts to build Asian networks of scientific activity, characterized by the circulation of experts, scientific knowledge, and specimens, provide the grounds for considering a practice of Pan-Asianism. Such a formulation adds to existing work on the Pan-Asianist articulations of intellectual and political figures and urges for an expansion of how we understand scientific activity across China and India from the 1930s to the 1960s. In so doing, the paper makes two historiographical interventions. In the first instance, the collaboration presents an opportunity to move beyond the two dominant frames through which histories of science in China and India are studied: the nation state and Non-West/West binaries. Second, a focus on science widens the scope of China–India history, a field dominated by research on cultural, intellectual, and diplomatic topics.