Longbows, because of their narrow limbs and rounded cross-section (which does not spread out stress within the wood as evenly as a flatbow’s rectangular cross section), need to be less powerful, longer or of more elastic wood than an equivalent flatbow. In Europe the last approach was used, with yew being the wood of choice, because of its high compressive strength, light weight, and elasticity. Yew is the best widespread European timber that will make good self longbows, (other woods such as Elm can make longbows but require heat treating of the belly and a wider belly/narrower back, while still falling into the definition of a longbow) and has been the main wood used in European bows since Neolithic times. More common and cheaper hard woods, including elm, oak, hickory, ash, hazel and maple, are good for flatbows. A narrow longbow with high draw-weight can be made from these woods, but it is likely to take a permanent bend (known as "set" or "following the string") and would probably be outshot by an equivalent made of yew.