The Hopi maintain a complex religious and mythological tradition stretching back over centuries. However, it is difficult to definitively state what all Hopis as a group believe. Like the oral traditions of many other societies, Hopi mythology is not always told consistently and each Hopi mesa, or even each village, may have its own version of a particular story. But, "in essence the variants of the Hopi myth bear marked similarity to one another." It is also not clear that those stories which are told to non-Hopis, such as anthropologists and ethnographers, represent genuine Hopi beliefs or are merely stories told to the curious while keeping safe the Hopi's more sacred doctrines. As folklorist Harold Courlander states, "there is a Hopi reticence about discussing matters that could be considered ritual secrets or religion-oriented traditions." David Roberts continues that "the secrecy that lies at the heart of Puebloan [including Hopi] life...long predates European contact, forming an intrinsic feature of the culture." In addition, the Hopis have always been willing to assimilate foreign religious ideas into their cosmology if they are proven effective for such practical necessities as bringing rain. As such, it is important to note that the Hopi had at least some contact with Europeans beginning the 16th century, and some believe that European Christian traditions may have entered into Hopi cosmology at some point. Indeed, Spanish missions were built in several Hopi villages starting in 1629 and were in operation until the Pueblo Revolt of 1680. However, after the revolt, it was the Hopi alone of all the Pueblo tribes who kept the Spanish out of their villages permanently, and regular contact with whites did not begin again until nearly two centuries later. The Hopi mesas have therefore been seen as "relatively unacculturated" at least through the early twentieth century, and it may be posited that the European influence on the core themes of Hopi mythology was slight.
[According to my knowledge (Lybertha's) they were recorded in 1976, but I won't claim to be right.]