In his narratives, Milescu summed up the knowledge that Russian explorers had gathered about East Siberia. Although he believed that the Amur was the largest river in the world, he listed its main tributaries without mistake. His idea that there was a vast mountain range stretching from the Baikal to the Okhotsk Sea, although fundamentally wrong, was widely believed by many geographers until the mid-20th century. He also heard rumours about Sakhalin, which he supposed to be the same island as Hokkaidō, thus considerably exaggerating its dimensions.