Estimated time when the subregions show the most compact configuration (minimum distances). Shown is the summed distance from each region to every other region at each time step (for ±20 Myr with 0.1 Myr timesteps), normalized to the maximum. The blue shaded area shows 1σ uncertainties, calculated by sampling the standard deviations around the averages. Left: the summed distances were calculated for all 14 investigated regions, which leads to a minimum at −6.0 Myr. Right: the summed distances were only calculated for nine regions by excluding the tail of Orion A. When excluding the tail the minimum gets more pronounced and shifts to −6.8 Myr. Beyond these minima the distances start to rise again (gray shaded areas), which means that any motions of the clouds before about −6 Myr should be omitted.