Because it can be confusing.  Since I don’t want to put spoilers, this will be relatively simplified.  I might update this post if I realize I forgot something.

Sengoku Era
-Lightning destroys the Fallen Jewel
-The prophecy is told

1986
-Marie-Antoinette Akiyama turns 20

1989
-Mikhail Akiyama dies

1998
-Events of Millennium Match
-Sekihara Katsumi turns 13

2000
-Year of prophecy
-Sekihara Shiro dies in a lightning storm

2005
-Events of Intrusion 20
-Crossroads Academy is destroyed in a fire

2006
-Events of Millennium Body 2
-Marie-Antoinette Akiyama turns 40

2011
-Toriyama Nara (11) describes the events of Millennium Match to Seino Rie (11)

2017
-Events of Crossroads 32 and Duel 32

2036
-Foreword is written