the main sources of the history of the lahngau are copies made in the high middle ages of older documents. there is always the question whether these documents were based on original sources or produced as counterfeits. if they were based on original manuscripts, some of which would have been 500 years old, it is often unclear whether they were reproduced literally or only paraphrased. the persons named in the documents may not always be clearly identifiable. place names are often in unusual forms and do not always correspond to the same names today. complete overviews of property ownership for this area only exist from the 12th century, so the opportunity to draw inferences is limited. archaeological finds that are available for review are often random finds, for example in the context of modern construction. many suspected archaeological sites have not been systematically investigated. for these reasons, some important questions about the history of the lahngau remain unsettled.