Complex sentence: Cattle grazing continued on the hill unabated until 1969, vehicle traffic was tolerated on parts of the hill until 1971, people picnicking or just sightseeing from their car were common sights in summer months.
Split into simpler sentences: Cattle grazing continued on the hill unabated until 1969. People picnicking or just sightseeing from their cars were common sights in summer months.