Пётр Петрович
Pyotr Petrovich Semyonov or Semenov (; 2 January "", 1827 – 26 February "", 1914) was a Russian geographer and statistician who managed the Russian Geographical Society for more than 40 years. He gained international fame for his pioneering exploration of the Tian Shan mountains. He was decreed to change his surname to "Semyonov of Tian Shan" (Семёнов-Тян-Шанский, "Semyonov-Tyan-Shansky") at the age of 79.