Scholars such as
Jaan Puhvel,
J. P. Mallory, and
Douglas Q. Adams have reconstructed aspects of the ancient
Proto-Indo-European religion, from which the religions of the various
Indo-European peoples derive, and that this religion was an essentially naturalist numenistic religion. An example of a religious notion from this shared past is the concept of
*dyēus, which is attested in several distinct religious systems. In many civilizations, pantheons tended to grow over time. Deities first worshipped as the patrons of cities or places came to be collected together as empires extended over larger territories. Conquests could lead to the subordination of the elder culture's pantheon to a newer one, as in the Greek
Titanomachy, and possibly also the case of the
Æsir and
Vanir in the
Norse mythos. Cultural exchange could lead to "the same" deity being renowned in two places under different names, as seen with the Greeks, Etruscans, and Romans, and also to the cultural transmission of elements of an extraneous religion into a local cult, as with worship of the
ancient Egyptian deity
Osiris, which was later followed in
ancient Greece.
Max Weber's 1922 opus
Economy and Society discusses a tendency of the ancient Greek philosophers to interpret gods worshiped in the pantheons of other cultures as "equivalent to and so identical with the deities of the moderately organized Greek pantheon". In other instances, however, national pantheons were consolidated or simplified into fewer gods, or into a single god with power over all of the areas originally assigned to a pantheon. For example, in the ancient Near East during the first millennium BCE,
Syrian and
Palestinian tribes worshiped much smaller pantheons than had been developed in Egypt and Mesopotamia. Weber also identified the link between a pantheon of gods and the development of
monotheism, proposing that the domination of a pantheon by a particular god within that pantheon was a step towards followers of the pantheon seeing that god as "an international or universal deity, a transnational god of the entire world". A similar process is thought to have taken place with respect to the Israelite deity
Yahweh, who, "as a typical West Semitic deity... would have four or five compatriot gods in attendance as he became the national high god". ==Extension of the concept into structures and celebrities==