  In this work we examine M dwarf rotation rates at a range of ages to
establish benchmarks for Mdwarf gyrochronology. This work includes a sample of
713 spectroscopically-classified M0-M8 dwarfs with new rotation rates measured
from K2 light curves. We analyzed data and recover rotation rates for 179 of
these objects. We add these to rotation rates for members of clusters with
known ages (5-700 Myr), as well as objects assumed to have field ages ($>$1
Gyr). We use Gaia DR2 parallax and (G-GRP) photometry to create color-magnitude
diagrams to compare objects across samples. We use color-period plots to
analyze the period distributions across age, as well as incorporate Halpha
equivalent width and tangential velocity where possible to further comment on
age dependence. We find that the age of transition from rapid to slow rotation
in clusters, which we define as an elbow in the period-color plots, depends on
spectral type. Later spectral types transition at older ages: M4 for Praesepe
at 700 Myr, one of the oldest clusters for which M dwarf rotation rates have
been measured. The transition from active to inactive Halpha equivalent width
also occurs at this elbow, as objects transition from rapid rotation to the
slowly rotating sequence. Redder or smaller stars remain active at older ages.
Finally, using Gaia kinematics we find evidence for rotation stalling for late
Ms in the field sample, suggesting the transition happens much later for mid to
late-type M dwarfs.
