if your Duldung is valid and you have the sentence in it that your residence (means: moving freedom) is limited to Bundesgebiet (whole Germany), you can travel and stay for a while everywhere in Germany but you are oblige to live in your place in Thuringen, you can only change it with a permission of the Ausländerbehörde and for that you must have a very special reason like a wife or a child somewhere, sometimes they permit it for work or prof. training.
If your Duldung is expired, you must go back to Thuringen and prolong it, the Ausländerbehörde in your place there is responsible. It can be that you will be punisched (mostly if you were illegal for long time). If you stay illegal for more time, your punishment can be worse. If you are interested in a perspective in Germany, you must know that any penalty through a civil court (Amtsgericht) for staying in Germany without permission (unerlaubter Aufenthalt) which is 90 daily rates (Tagesätze) or more, makes many important things impossible like Ausbildungsduldung, Beschäftigungsduldung, a permission for work, some kinds of residence permit usw.