Older T-Tauri stars are poorly understood even though they offer key insight to understanding evolution of lower-mass ( 0.1 - 2 M_sun) stars and of protoplanetary discs. We present a study of photometric variability of 2000 confirmed 4-10 Myr T-Tauri stars in the Orion OB1 association using optical time-series from three different surveys: the Centro de Investigaciones de AstronomÃa-Quest Equatorial Survey Team (CIDA-QUEST), the Young Exoplanet Transit Initiative (YETI) and from a Kitt Peak National Observatory (KPNO) campaign. We investigated stellar properties such as rotation period and amplitude of variability based on star type and location to look for population-wide trends. We detected 143 periodic variables and 1057 irregular variables by investigating the light curves of these stars; the periodic properties of the remainder 800 stars are inconclusive because of few data points or ambiguous light curves. We find that 12.36% of Weak-line T-Tauri stars (WTTS) and 7.97% of Classical T-Tauri stars (CTTS) are periodic. We did not find any noticeable difference in rotation period between CTTS and WTTS. In contrast, our study provides observational evidence of rotational evolution between 4 Myr and 10 Myr stars with the young ones having longer rotation periods. We also confirm the well known pattern of large amplitude variability among CTTS when compared to WTTS, likely the result of the effect of the interaction between the protoplanetary discs and the central star in the CTTS systems.