﻿CLIMATE 
  AND 
  MIGRATION 
  CURRY 
  431 
  

  

  After 
  the 
  fifth, 
  most 
  disastrous 
  period, 
  modern 
  Europe 
  hegins 
  to 
  

   emerge 
  from 
  the 
  chaos 
  of 
  the 
  Dark 
  Ages. 
  After 
  the 
  sixth 
  and 
  last 
  

   irruption 
  from 
  the 
  steppes 
  the 
  Renaissance 
  ushers 
  in 
  the 
  present 
  age. 
  

  

  Taking 
  the 
  periods 
  after 
  600 
  B. 
  C. 
  as 
  being 
  more 
  precisely 
  dated, 
  

   it 
  is 
  clear 
  that 
  each 
  complete 
  climatic 
  cycle 
  had 
  an 
  average 
  duration 
  

   of 
  approximately 
  640 
  years. 
  The 
  years 
  1170 
  A. 
  D., 
  530 
  A. 
  D., 
  and 
  

   100 
  B. 
  C. 
  indicate 
  the 
  crests 
  of 
  the 
  waves 
  of 
  migration 
  and 
  drought. 
  

   Proceeding 
  further 
  back, 
  if 
  the 
  same 
  figure 
  held 
  good 
  the 
  next 
  three 
  

   crests 
  would 
  be 
  represented 
  by 
  the 
  years 
  750 
  B. 
  C, 
  1390 
  B. 
  C, 
  and 
  

   2030 
  B. 
  C; 
  and 
  these 
  dates 
  accord 
  with 
  the 
  general 
  estimate 
  of 
  the 
  

   duration 
  of 
  the 
  first 
  three 
  migrator}^ 
  periods 
  as 
  indicated 
  in 
  previous 
  

   paragraphs. 
  It 
  may, 
  therefore, 
  be 
  inferred 
  for 
  the 
  present 
  that 
  these 
  

   dates 
  provide 
  a 
  measuring 
  rod 
  for 
  the 
  history 
  of 
  the 
  2,500 
  years 
  

   preceding 
  our 
  era. 
  An 
  attempt 
  has 
  been 
  made 
  to 
  represent 
  the 
  histor- 
  

   ical 
  movements 
  in 
  graph 
  D 
  on 
  page 
  432. 
  

  

  An 
  analysis 
  of 
  physiographic 
  and 
  of 
  historical 
  data 
  leads 
  then 
  to 
  

   the 
  following 
  conclusions 
  : 
  

  

  (1) 
  A 
  regular 
  succession 
  of 
  climatic 
  cycles 
  approximately 
  640 
  

   years 
  in 
  duration, 
  each 
  including 
  on 
  the 
  average 
  something 
  like 
  

   300 
  years 
  of 
  increasing 
  aridity, 
  has 
  produced 
  a 
  series 
  of 
  alternating 
  

   periods 
  of 
  migration 
  and 
  consolidation 
  in 
  Europe 
  and 
  Asia, 
  where 
  

   the 
  effects 
  can 
  be 
  traced 
  between 
  the 
  years 
  2300 
  B. 
  C. 
  and 
  1600 
  A. 
  D. 
  

  

  (2) 
  These 
  periods 
  of 
  migration 
  have 
  also 
  been 
  periods 
  of 
  internal 
  

   decay 
  in 
  civilized 
  states 
  and 
  among 
  settled 
  communities. 
  This 
  would, 
  

   A 
  priori, 
  be 
  expected 
  to 
  result 
  from 
  unsettled 
  and 
  particularly 
  de- 
  

   teriorating 
  conditions 
  of 
  climate 
  causing 
  deterioration 
  in 
  the 
  agri- 
  

   cultural 
  and 
  commercial 
  conditions 
  under 
  which 
  the 
  people 
  of 
  such 
  

   communities 
  lived. 
  

  

  It 
  may 
  be 
  deduced 
  that 
  the 
  periods 
  of 
  consolidation 
  would 
  ne- 
  

   cessarily 
  be 
  such 
  that 
  conditions 
  were 
  relatively 
  "settled" 
  in 
  every 
  

   respect; 
  that 
  is 
  to 
  say, 
  when 
  at 
  the 
  most 
  very 
  slight 
  variations 
  of 
  

   climate 
  occurred. 
  

  

  (3) 
  Physiographic 
  conditions 
  generally 
  (c. 
  f. 
  the 
  graph 
  and 
  other 
  

   evidence 
  relating 
  to 
  the 
  levels 
  of 
  the 
  Caspian 
  Sea) 
  prove 
  that, 
  taking 
  

   the 
  period 
  of 
  the 
  last 
  7000 
  years 
  as 
  a 
  whole, 
  there 
  has 
  been 
  a 
  large- 
  

   scale 
  but 
  very 
  gradual 
  tendency 
  towards 
  desiccation. 
  

  

  From 
  this 
  it 
  may 
  be 
  inferred 
  that 
  the 
  300-year 
  periods 
  of 
  migration 
  

   have 
  been 
  of 
  such 
  a 
  nature 
  that 
  this 
  general 
  primary 
  tendency 
  has 
  been 
  

   accelerated 
  by 
  secondary 
  conditions, 
  and 
  that 
  the 
  300-year 
  periods 
  of 
  

   consolidation 
  have 
  been 
  of 
  such 
  a 
  nature 
  that 
  the 
  corresponding 
  

   secondary 
  conditions 
  have 
  served 
  more 
  or 
  less 
  closely 
  to 
  counteract 
  

   this 
  general 
  tendency. 
  

  

  This 
  general 
  tendency 
  is 
  reflected 
  in 
  history 
  by 
  a 
  tendency 
  for 
  

   the 
  centers 
  of 
  civilization 
  to 
  move 
  gradually 
  away 
  from 
  the 
  equator. 
  

   Prior 
  to 
  1000 
  B. 
  C. 
  conditions 
  were 
  most 
  favorable 
  to 
  physical 
  and 
  

  

  