After some ten years of development, which Zamenhof spent translating literature into Esperanto, as well as writing original prose and verse, the first book of Esperanto grammar was published in Warsaw on July 26, 1887. The number of speakers grew rapidly over the next few decades; at first, primarily in the Russian Empire and Central Europe, then in other parts of Europe, the Americas, China, and Japan. In the early years before the world congresses, speakers of Esperanto kept in contact primarily through correspondence and periodicals.
