Venus was not mentioned by ancient astronomers until after 2000 BCE, which indicates that this planet was not to be found in it's present, prominent position prior to this time.
Venus tablets:
Lost in the debate over the chronological significance of these
early observations is the question why Venus would have
been the subject of such intense scrutiny in the first half of
the second millennium, much less why it was associated
with typically dire omens? On this subject, Abraham Sachs,
the dean of Babylonian cuneiform texts, offers nary a clue:
"The list of Venus dates, to which omen predictions were
secondarily appended, was copied and recopied for many
centuries, and, in fact, we have it only in the form of much
later copies made in the eighth and later centuries BC (and
with partly corrupt details) embedded in one of the tablets
of a standard collection of astronomical and meteorological
omens. How, when, and why omen predictions--...--were
attached to the Venus dates are questions that we cannot begin to
answer in the present state of our knowledge." ("Babylonian
observational astronomy," Phil. Trans. R. Soc. Lond. A, 276,
1974, pp. 43-44).
http://www.bearfabrique.org/Catastrophism/venus/vcycle
The following is from an article by
Lynn E. Rose from the Winter 73 issue (#III) of the Pensee Journal,
the old Student Academic Freedom Forum
"Unfortunately, nearly all treatments of groups one and three
on K. 160, and of the genuinely observational material on the
other Venus tablets that supplement K. 160, have been based on
what I call the "astronomer's dogma". The "astronomer's
dogma" is the uniformatarian attitude that the solar system
has for untold years been just as it is now, and that Venus
and Earth in particular have always been on the same orbits
they are on now, except for certain very minor perturbations
that are for most purposes entirely negligible.
"The next major study of the Venus tablets was by Langdon and
Fotheringham in 1928. Their book is important for the student
of the tablets in that they bring together a great deal of
material that is not available in any one other place;
unfortunately, however, their book is dominated and severely
handicapped by the astronomer's dogma, and they find it
necessary to scoff at much of what the tablets say was
actually seen, simply because such things are not seen today."
Indian and Central American records also show Venus moving on
an orbit other than its present one. Ginenthal cites Evan
Hadingham ("Early Man and the Cosmos):
"The Venus pages [of the Dresden Codex] bear little
resemblance to a modern astronomical table."
http://www.skepticfiles.org/neocat/ammi.htm