Official language after unifying the country in 221 BC. Classical Chinese would remain the standard written language for the next 2000 years. Standardization of the spoken language received less political attention, and Mandarin developed on an "ad hoc" basis from the dialects of the various imperial capitals until being officially standardized in the early twentieth century. According to an undated chart by the American pro-English-only organization known as U.S. English, 178 countries have an official language at the national level. Among those, English is the most common with 67 nations giving it official status. French is second with 29 countries, Arabic is
Ecoregions of Zambia artificial reservoir), together with the smaller lakes such as Mweru Wantipa and Itezhi-Tezhi reservoir, and numerous lagoons and swamps cover about 5% of Zambia. Together with their associated rivers, the WWF categorises these freshwater bioregions in Zambia: Zambezi Basin made up of (not shown on the map): Ecoregions of Zambia The biomes and ecoregions in the ecology of Zambia are described, listed and mapped here, following the World Wildlife Fund's Global 200 classification scheme for terrestrial ecoregions, and the WWF freshwater bioregion classification for rivers, lakes and wetlands. Zambia is in the Afrotropic biogeographic realm (or ecozone) of the scheme.