Surviving information about Baltic mythology in general is fragmented. As with most ancient Indo-European cultures (e.g. Greece and India), the original primary mode of transmission of seminal information such as myths, stories, and customs was oral, the then-unnecessary custom of writing being introduced later during the period of the text-based culture of Christianity. Most of the early written accounts are very brief and made by foreigners, usually Christians, who disapproved of pagan traditions. Some academics regard some texts as inaccurate misunderstandings or even fabrications. In addition, many sources list many different names and different spellings, thus sometimes it is not clear if they are referring to the same thing.