[1] During the first decade of the 20th century, when the Great Game reached its peak, Kozlov rivaled Sven Hedin and Aurel Stein as the foremost researcher of Xinjiang.

Although he was on good terms with Hedin and other foreign explorers, the British government, as represented by George Macartney, monitored his movements across Central Asia.

[5] After bringing to Petrograd some amazing samples of 2000-year-old Bactrian textiles, Kozlov retired from scientific work and settled in a village near Novgorod.

Kozlov married Elizabeth Kozlova, a woman 29 years his junior, who accompanied him on his final journey of exploration as the expedition ornithologist, and who was to publish many monographs and scientific papers on the avifauna of Central Asia.

In 1904, the botanist Vladimir Ippolitovich Lipsky published a genus of flowering plants from Central Asia (belonging to the family Apiaceae) as Kozlovia, in Pyotr Kozlov's honour.