Time Reckoning & Historical Periods

Natural Basis of Time Measurement

• Earth’s rotation ⇒ day/night
• Moon’s orbit around Earth ⇒ lunar month
• Earth’s orbit around Sun ⇒ solar year & seasons

Reading Thai Lunar Dates

• Pattern: \text{[weekday]} \text{Khuen/Raem} [day] \text{Month} [lunisolar\,month]
• Symbols
  • Front digit 9–7 ⇒ \text{Sun}=9 \dots Sat=7
  • Digit 1 above line ⇒ waxing (ข้างขึ้น); below ⇒ waning (ข้างแรม)

Thai & Related Eras

• พ.ศ. (B.E.) begins at 1 (Buddha’s passing +1 yr); official use from 21 Feb 2455 (Rama 6)
• ม.ศ. (Saka) = B.E. -621
• จ.ศ. (Minor) = B.E. -1181
• ร.ศ. (Rattanakosin) : R.S. 1 = B.E. 2325; discontinued B.E. 2455
• ค.ศ. (C.E.) : C.E. 1 = B.E. 544
• ฮ.ศ. (Hijri) : H.E. 1 = C.E. 622 (lunar yr 354 d); ≈ B.E. = H.E. +1122

Conversion Formulae

• \text{B.E.}=\text{Saka}+621
• \text{B.E.}=\text{Minor}+1181
• \text{B.E.}=\text{R.S.}+2324
• \text{B.E.}=\text{C.E.}+543
• \text{B.E.}=\text{Hijri}+1122
  (reverse by subtraction)

Multi-Year Groupings

• ทศวรรษ (decade): years ending 0–9 e.g. 2020–2029
• ศตวรรษ (century): years 01–00 e.g. 101–200
• สหัสวรรษ (millennium): years 000 e.g. 1001–2000

Prehistoric Periods (by tools)

• ยุคหินเก่า (Palaeolithic): nomadic; rough stone tools
• ยุคหินกลาง (Mesolithic): finer tools; domestication; boats
• ยุคหินใหม่ (Neolithic): settled farming; pottery; weaving
• ยุคสำริด (Bronze): alloy \text{Cu}+\text{Sn}; bronze tools
• ยุคเหล็ก (Iron): iron smelting & durable tools

Prehistoric Periods (by livelihood)

• Hunter-gatherer communities
• Village agriculture
• Urban societies

Historic Age

• Begins with invention of writing; written records of politics, economy, society, culture

World History Periodisation

• Ancient
• Medieval
• Modern
• Contemporary

Thai History Periodisation

• By kingdoms (e.g. สุโขทัย, อยุธยา…)
• By capitals
• By individual reigns