[en] The relatively large measured value of θ₁₃ has opened up the possibility of determining the neutrino mass hierarchy through earth matter effects. Amongst the current accelerator experiments only NOvA has a long enough baseline to observe earth matter effects. However, even NOvA is plagued with uncertainty on the knowledge of the true value of Δ _CP which drastically reduces its sensitivity to the neutrino mass hierarchy. Earth matter effects in atmospheric neutrinos on the other hand is almost independent of δ_CP. The 50 kton magnetized Iron CALorimeter at the India-based Neutrino Observatory (ICAL at the rate lNO) will be observing atmospheric neutrinos. The charge identification capability of this detector gives it an edge over others for mass hierarchy determination through observation of earth matter effects. We study in detail the neutrino mass hierarchy sensitivity of the data from this experiment simulated using the Nuance based generator developed for ICAL at the rate lNO and folded with the detector resolution and efficiencies obtained by the INO collaboration from a full detector Geant based simulation. The data from ICAL at the rate lNO is then combined with simulated of T2K, NOvA Double Chooz, RENO and Daya Bay experiments and a combined sensitivity study to the mass hierarchy performed. With 10 years of ICAL at the rate lNO data combined with T2K, NOvA and reactor data, one could get 2.8σ - 5σ discovery for the neutrino mass hierarchy depending on the true value of (θ23, θ13 and δ_CP. (author)