You can travel through the Himalayas alone, but your experience might not be as enriching as it could have been with a guide. The trekking guides know every hidden treasure and exciting areas of the region, which you might not find out on your own. With trekking guides, there is no chance of getting lost. Also, they are well-trained to assist you in case of accidents or any emergency conditions. Therefore, guides are not completely necessary, but it becomes a much more relaxed and better experience if you have a trekking guide with you. Restricted areas cannot be traveled alone and needs special permits and a guide.