Active Galactic Nuclei (AGN) are amongst the most luminous sources of radiation in the Universe, and are powered by accretion of matter onto a supermassive black hole (SMBH). In the last years it has become evident that AGN have played an important role in the evolution of galaxies, even though the mechanism responsible for the interaction between the accreting system and the host galaxy is still poorly understood.

A first fundamental step to understand the relationship between AGN and their host galaxies is to assess how the accreting system influences the material within few parsecs from the SMBH. In my talk, I will discuss the importance of X-ray observations to study the circumnuclear material in AGN, reviewing some of the most recent works on this subject. I will also show how we will be able to use X-ray reflection features both above and below 10 keV to understand the structure and evolution of the circumnuclear material exploiting the unprecedented and revolutionary spectral and polarimetric capabilities of ASTRO-H.