The first quasars at the Reionisation Epoch, z ∼ 6-7.5, probe the early stages of supermassive black holes and host galaxy assembly. In this paper, we present recent results, exploiting VLT, ALMA and NOEMA observations, that allow us to constrain the onset of strong black hole feedback, the dust properties and star formation rates in high redshift quasars with unprecedented accuracy. These results highlight the strategic importance of ALMA high frequency (i.e. Band 9 and 8) observations to obtain a reliable overview of the host galaxy and supermassive black hole growth out to the highest redshifts.
