  We performed numerical simulations of the obliquity evolution of Mars during
the Noachian era, at which time the giant planets were on drastically different
orbits than today. For the preferred primordial configuration of the planets we
find that there are two large zones where the Martian obliquity is stable and
oscillates with an amplitude lower than 20$^\circ$. These zones occur at
obliquities below 30$^\circ$ and above 60$^\circ$; intermediate values show
either resonant or chaotic behaviour depending on the primordial orbits of the
terrestrial planets.
