Wooden poles connect the lattice-work on the bottom of the yurt to the shangrak (the hole in the middle of the tent for the smoke to escape). This wood frame (kerege) is then covered with felt and then usually with canvas.
Mongolian Ger; 2003 picture by Robert Matthews
The shangrak itself is emblematic in many Central Asian cultures. A stylized version of the shangrak forms the main image on the flag of Kyrgyzstan. In old Kazakh communities, the yurt itself would often be repaired and rebuilt, but the shangrak would remain intact, passed from father to son upon the father's death. A family's depth of heritage could be measured by the accumulation of stains on the shangrak from generations of smoke passing through it.
Followers of the New Age religion have used the name "yurts" for some their huts as well. Although those structures may be copied to some extent from the originals found in Central Asia, they have been greatly changed and adapted and are in most cases very different.
In Europe, most yurt makers are making adaptations of Mongolian and Turkic style yurts from local hardwoods and canvas. Unlike many US manufacturers these yurts are very similar to those found in central Asia. In Holland one yurt maker makes exact replicas of Mongolian Gers.