The literary Ukrainian language, which was preceded by Old East Slavic literature, may be subdivided into three stages: old Ukrainian (twelfth to fourteenth centuries), middle Ukrainian (fourteenth to eighteenth centuries), and modern Ukrainian (end of the eighteenth century to the present). Much literature was written in the periods of the old and middle Ukrainian language, including legal acts, polemical articles, science treatises and fiction of all sorts.Influential literary figures in the development of modern Ukrainian literature include the philosopher Hryhori Skovoroda, Mykola Kostomarov, Mikhaylo Kotsyubinsky, Taras Shevchenko, Ivan Franko, and Lesia Ukrainka. The literary Ukrainian language is based on the dialect of the Poltava region, with some heavy influence from the dialects spoken in the west, notably Galicia (Halychyna). For most of its history, Russian letters were used for written Ukrainian (for example, by Shevchenko). The modern Ukrainian alphabet and orthography, which introduced the distinct letters і, ї, є, ґ, and modified the usage of и, was developed in the late nineteenth century in Austrian-controlled Galicia.