To try to solve the puzzle of how the infection persisted and spread over thousands of years in Eurasia, an international team of researchers from the Max Planck Institute of Infection Biology, Harvard University, the University of Arkansas, the Max Planck Institute of Evolutionary Anthropology, and Seoul National University investigated the bones and teeth of Bronze Age livestock at the pastoralist site Arkaim (Russia), a Eurasian Steppe site belonging to the Sintashta-Petrovka culture known for its innovations in cattle, sheep, and horse husbandry. There they identified a 4,000-year-old sheep infected with the same LNBA lineage of Y. pestis that was infecting people at the time.