Depending on your requirements you can populate the tree view control using different sources.

Here I give the example for populating the asp .net menu using sitemap.
private void CreateMenuControl()
{

Menu1.DataSource = GetSiteMapDataSource();
Menu1.DataBind();

}

private SiteMapDataSource GetSiteMapDataSource()
{
XmlSiteMapProvider xmlSiteMap = new XmlSiteMapProvider();
System.Collections.Specialized.NameValueCollection myCollection = new System.Collections.Specialized.NameValueCollection (1);
myCollection.Add("siteMapFile", "Web.sitemap");
xmlSiteMap.Initialize("provider", myCollection);
xmlSiteMap.BuildSiteMap();

SiteMapDataSource siteMap = new SiteMapDataSource();

return siteMap;
}