Current searches for dark matter at the LHC focus on mono-X signatures where the production of dark matter in association with a Standard Model (SM) particle is considered. The simplest benchmark model involves a massive spin-1 mediator, the Z′ boson, between the dark matter χ and the SM. Limits derived from mono-X channels are most effective when the mediator can decay into two on-shell dark matter particles, i.e. when M(Z′)≳2Mχ. In this talk, I will be discussing how the experimental region can be broadened to include cases where the Z’ is considerably lighter than twice the dark matter mass. In this scenario, the Z′ mediates an effective long-range force between the dark matter, thereby facilitating the formation of a bound state as is common in many dark sector models, which we call ‘darkonium’. The darkonium becomes active when Mχ>M(Z′)*αeff, where αeff is the effective fine-structure constant in the dark sector. Moreover, the darkonium could decay back into SM quarks, without producing missing transverse momentum in the detector. Considering multijet final states, especially dijet resonance searches at the LHC, we reinterpret existing searches to constrain the simple Z′ benchmark beyond the region probed by mono-X searches. Assuming a baryonic Z′ mediator and a Dirac dark matter, direct detection bounds can be loosened by giving a small Majorana mass to the dark matter. We also consider the interplay between mono-X and darkonium channels at future high energy colliders, which is at the frontier of probing the model parameter space.