Historical eras are often defined differently across cultures. Some cultures, like those influenced by monarchies, name periods after their rulers. Taylor Swift even adopted this concept for her musical "Eras." Thai culture, however, employs its own system for timekeeping, using Buddhist benchmarks instead of the BC/AD system. Furthermore, Thai historical eras are named after their capital cities, showcasing a unique approach. The Ayutthaya Era was the longest, followed by the brief Thonburi Era. The Rattanakosin Era succeeded these, lasting until 1932. Rattanakosin Island, now part of Bangkok, became heavily fortified during the Thonburi period. By the Rattanakosin Era, the island was almost entirely surrounded by defensive walls. The obsolescence of these fortifications arose with Bangkok's expansion and subsequent peace, leading to their removal and leaving only a few remnants today.