This study investigates the high-pressure chemistry of yttrium hydrides and carbides synthesized using ammonia borane (NH3BH3) and paraffin oil as hydrogen precursors in laser-heated diamond anvil cells (DACs) up to 171 GPa and 3000 K. Synchrotron single-crystal x-ray diffraction (SCXRD) revealed five previously unknown yttrium hydrides: hP3-Y3H1, hP2-Y2H3, cP8-Y4H23, hP26-Y13H76, and cF80-Y4H13, along with two previously unknown yttrium allotropes (hP3-Y1 and tI8-Y) and a yttrium carbide (YC6). The hydrogen content in the hydrides was estimated based on empirical relations and ab initio calculations, showing an increase with pressure, from YH3 at 87 GPa to YH6.25 at 171 GPa. The study also identified a carbide (YC6) and two yttrium allotropes, highlighting the complex phase diversity and variable hydrogen content in yttrium hydrides. Ab initio calculations revealed the metallic nature of these compounds, complicating the identification of superconducting phases and understanding electronic transitions in high-pressure synthesized materials. The results demonstrate the broad compositional and structural variety of possible phases in the Y-NH3BH3 and Y-paraffin oil systems, underscoring the challenges in accurately determining the chemical compositions and structures of high-pressure materials. The findings contribute to the understanding of high-pressure chemistry and the potential for high-temperature superconductivity in yttrium hydrides.This study investigates the high-pressure chemistry of yttrium hydrides and carbides synthesized using ammonia borane (NH3BH3) and paraffin oil as hydrogen precursors in laser-heated diamond anvil cells (DACs) up to 171 GPa and 3000 K. Synchrotron single-crystal x-ray diffraction (SCXRD) revealed five previously unknown yttrium hydrides: hP3-Y3H1, hP2-Y2H3, cP8-Y4H23, hP26-Y13H76, and cF80-Y4H13, along with two previously unknown yttrium allotropes (hP3-Y1 and tI8-Y) and a yttrium carbide (YC6). The hydrogen content in the hydrides was estimated based on empirical relations and ab initio calculations, showing an increase with pressure, from YH3 at 87 GPa to YH6.25 at 171 GPa. The study also identified a carbide (YC6) and two yttrium allotropes, highlighting the complex phase diversity and variable hydrogen content in yttrium hydrides. Ab initio calculations revealed the metallic nature of these compounds, complicating the identification of superconducting phases and understanding electronic transitions in high-pressure synthesized materials. The results demonstrate the broad compositional and structural variety of possible phases in the Y-NH3BH3 and Y-paraffin oil systems, underscoring the challenges in accurately determining the chemical compositions and structures of high-pressure materials. The findings contribute to the understanding of high-pressure chemistry and the potential for high-temperature superconductivity in yttrium hydrides.