What is "zendikar"

The Zendikar block is a Magic: The Gathering block consisting of the sets Zendikar (October 2, 2009), Worldwake (February 5, 2010), and Rise of the Eldrazi (April 23, 2010). The eponymous setting is a vast, untamed wilderness, whose few bastions of civilization exist primarily for outfitting treasure-seeking expeditions to distant locales. Colossal ancient octahedral stones called "hedrons" float in the sky (hedrons are the expansion symbols for all three blocks). A phenomenon known as "the Roil" causes frequent geological upheaval as it sweeps across the land. Unlike the previous two blocks, there is no multicolored theme (in fact, every colored card in the set is monocolored). Instead, the themes Zendikar and Worldwake revolve around lands, and a theme of an adventure or quest. Rise of the Eldrazi, while part of the Zendikar block creatively and for the sake of constructed tournament rules, is unique mechanically and is designed to be drafted on its own. Drafts in the Zendikar block are either ZEN-ZEN-WWK or ROE-ROE-ROE.