The response to your question may be best answered by explaining what historians do. Historical records are like a giant puzzle. Historians attempt to put the pieces of the historical puzzle together to complete the picture of the historical record of events. The puzzle pieces come in the form of primary source documents, secondary accounts, and maps. Sometimes the pieces are composed of archeological finds like shards of pottery, weaponry, or the remains of civilizations. It is the job of historians to, to the best of their ability, verify the authenticity of the sources of information and recreate events as accurately and factually as humanly possible.
Myths in history are important because they have symbolic and cultural meaning. The historian investigates myths without prejudice or dismissal until the facts no longer support the myth. Pocahontas (Amonute or Matoaka, her real names) is a significant person of historical interest in the founding of the American society. Her real-life is entangled in myth by the tales written in children's books and produced in movies. Popular culture is a powerful influence on how we perceive historical figures. She is no exception, as the legend has overshadowed the real-life accomplishments of Pocahontas well-documented by several credible scholars and historians. Historians from several decades have completed extensive research on her life to separate the myth from fact.
Maps are an essential source of information for historians, but they are only one part of the puzzle. Maps are problematic for historians, as verifying the accuracy and authenticating the source of the map is made difficult by the fact that many times, sites that once existed no longer exist. Cartographers in the sixteenth and seventeenth centuries did not have the tools we have today, and accuracy can be a problem. Maps can be controversial as different cultures exaggerate their claims. In some cases, they changed the names to fit their cultural norms. Historians view maps with the same level of skepticism as other materials.
The answer to your question is a map is one source of evidence in a historical record. A historian will not be swayed to believe one thing without sufficient supporting evidence and facts from many different sources. In the case of the mythical versus factual beliefs concerning Pocahontas, there is a great deal of credible research beyond maps that separate the myth from the facts. Although the puzzle is not fully complete, enough of the pieces are in place to get an accurate picture of the life of one of America's most exciting and significant historical figures.