The increasing prevalence of nanoparticles in the environment, resulting from both natural and anthropogenic activities, has raised important questions about their long-term ecological impacts. While conventional pollution monitoring techniques often focus on short-term or localized contamination, tree-ring chemistry offers a powerful means to investigate historical nanoparticle deposition across time and space. This chapter explores how trees can serve as long-term environmental recorders, capturing nanoparticle accumulation in annual growth layers, Tree-Rings. Emphasis is placed on the potential of tree ring chemistry, also known as dendrochemical analysis, to trace the movement, retention, and stability of metal-based nanoparticles introduced through atmospheric deposition and soil uptake. This chapter outlines the methodological advances and challenges of using tree rings as a natural archive for nanoparticle contamination. This interdisciplinary approach is significantly beneficial in environmental monitoring, regulation, and the development of bioindicators for the future in a nanoscale pollution era.