This is still under construction and revision but it's a good read:
even more time before about a billion years ago- the civilization d is from makes zinv and himc.
22 years before about a billion years ago - alien artifacts are found on earth by kazuki yotsuga's dad. the timeline splits in two.
about a billion years ago - on the original earth, the planet that eventually became the wau planet in gxp. dual! parallel trouble adventure happens. the two worlds merge. they journey into space and become the first members of the prehistoric civilization
^*18010 bc -Naja was born
^*18007 bc- Washu's containment facility fails washu wakes up and she later reverts to a kid and puts herself in an orphanage.
17998 bc- mikumo and miyuki are born
**3708 bc- Naja was attacked by pirates while she was on planet K1190 and she went missing. She was about 14302 years old, she was seto was found on the same planet by ushio kamiki who fought off the pirates. she appeared to be around 6.
**the late 700's(around 786)- at around 4,500 years old seto met utsutsumi when he fell on her she was 4,500 he was 9
the late 800's early 900's (around 916) at 139 utsutsumi proposed to seto
**1239- azusa is born to amame and kazuki
**1246 -funaho is born
**1247- azusa meets seto
**1249-asuza goes to jurai at age 10
**1252- azusa meets mitsuki and she dies
**1256-Misaki kamiki is born
**1260-Azusa at 21 meets funaho after battling kagato and becomes emperor(jurai novel)
**1266-azusa marries funaho who is 20 now
**1266 or 1267 airi is born("I'm three years and four months older than you"-airi to yosho she is about 727 in ova 3)(my mother is around twenty years older then me - the ova 4 intro doujin)
**1270-yosho born(according to jurai about 724 in ova 3)
**1275- azusa and misaki get married when she turns 19
**1278-Ayeka is born (according to jurai.)
*1282- yosho gets arranged to marry ayeka gets his tree goes to the galaxy academy & meets airi
*1287- airi refuses to claim asylum at the galaxy academy. she goes back to airi and airi becomes an isolationist state when seto puts a halt to kasens amaki's marriage. airi and yosho conceive minaho.
**1289-sasami is born(according to jurai novel they are 11 years different)
1292- ryoko attacks jurai and gets sealed in the cave sasami merges with tsunami at age 3 ayeka is 11 years older so she is 14. stated to be about 500,000 years after naja died.
1297- sasami and ayeka leave jurai at age 8 and 19 +695 years technically 703 and 716 at the begining of ova 1.
1716- Kiyone born
1913*-Tennyo is born
1969-mihoshi is born?
1974- noike is born/ illegaly de-aged from female kagato
1970- misao is born
1971- mashisu is born
1974***-when Kiriko is born she is 5 years older then seina. or 20
1977 -tenchi is born ***comparing his birthday to kirikos in gxp's beginning tenchi is 17
it makes sense They were possibly waiting for him to turn 18 to tell him about his mothers death. so this makes sense.
1979***-seina is born he is 15 when gxp starts they say he is 14 or 15 but they then say he is 15... but this is odd he is 15 and just graduating middle school. wouldn't put it past him though to have failed a grade
1982*** Yoshiko is born
1984* before june kiyone dies at 248 (ova 3 ep 1 yosho:"its been 10 years alread since kiyone died, she died at 248")
^*Summer break 1992 Tenchi ova 1 . at age 15 tenchi sets ryoko free
september 1st, 1992- ryoko blows up tenchi's school, its the first day of school, japan (one old poor source says ayekas birthday is september 21's if so she turns 717 shortly after landing on earth this explains sources saying she is 17 but she is 20) high schools come back on setember 1st from summer break. ayeka unfreezes sasami is 8 /703
^*October of 1992 – Ryo-ohki-chan is born. Ayeka discovers Funaho-tree and realizes that Yosho is still alive.
^*December of 1992 – Mihoshi crash-lands on Earth. Her shuttle falls into subspace. Kagato makes a comeback.
^*January of 1993 – Ryoko creates the Floating Onsen.
^*February of 1993- Kagato comes to Earth seeking the ultimate power. He kidnaps Ryoko. Katsuhito is revealed to be Yousho. Yousho gives Funaho-tree to Tenchi. Ryo-ohki-chan and the remains of Ryu-oh fuse into Ryu-ohki. Ryu-oh is destroyed, and so is Tenchi. Tsunami appears and resurrects him. Mihoshi releases Washu. Tenchi creates Light Hawk wings for the first time. Kagato is destroyed, and so is Soja.
^*March of 1993 – Ryu-oh is resurrected. Mihoshi’s shuttle is pulled out of subspace. She returns and submits her report. Masaki house is destroyed by Mihoshi’s shuttle.
^*April of 1993 – Nobuyuki rebuilds the Masaki house. The truth about the Sasami/Tsunami relationship is discovered. Ryo-ohki-chan fuses with Masu. Dr. Clay is assigned by Tokimi-sama to capture Washu. Zero replaces Ryoko. Washu and Dr. Clay duke it out after so many years. Dr. Clay explodes the lower portion of his ship. Tenchi uses Light Hawk Wings for the second time. Dr. Clay is captured and escorted to Galaxy Police. D3 erases Dr. Clay’s memories of his dealings with the Choushin. Z destroys a fleet of ships sent to attack Tokimi’s “temple.” Tokimi-sama issues a warning to Z to not touch Tenchi.
^*May of 1993 – A Jurai delegation arrives on Earth. The truth about Yosho is revealed. Funaho asks Washu not to make another Ryo-ohki. Washu assures her that it will never happen. Tenchi fights Seriyo and wins (thanks to Mihoshi).late May 1993- the prologue of the novel Yosho takes place ayeka's hair is reverted back to blue temporarily sasami is said to be 9 so she is 704.
summer 1993- OVA 3 in its entirety takes place. Noike arrives at age 20. Tenyo at 80 years old introduces herself to tenchi. time resets
around july 1993 the second time around: Seina gets a pamphlet from amane that mihoshi sends for in the ova 3 episode 6. why is it june? its summer. early summer. the rainy season. school is in session no after school activities due to the extrema heat (kai also calls and asks why he wasn't at school so schools still in session) he is 15 and he was in middle school about to graduate and be kept from entering high school because in japan its not mandatory they dint have to let him in. in japan summer is june to august summer break starts July 20. he already knows who noike is. he comes to visit but when he arrives the whole family is gone so they were probably away doing operation lovey dovey. which is close enough that soon after is:
september 1993 ova 4 starts its less then a month before noboyuki and rea's wedding as noted in ova 4 ep 1.
Summer 1994 seina returns home for the first time. rea is pregnant. Tenchi's kami powers are growing and speeding up his ageing.
fall 1994 - Kenshi is born after summer
summer 1995- volume 14 of gxp seina graduated from the academy. he goes home to earth and says has it already been two years already
sasami would be at least 11
sasami would be at least 11
summer 1996 - seina fights against HIMC in the end of volume 14 of gxp
sasami would be at least 12
fall 1999: The last episode of OVA 4 happens sasami would be 17 kenshi is 5
2001: sasami watches tenchi get rode like a horsey by noike when she is 17 kenshi is the year must be 2001 ayeka waits her turn
No juraian princess especially one as ayeka-y as ayeka would ever even humor the idea of taking turns mounting tenchi's master sword and summoning the power from his jewels outside of marriage. By 2001 tenchi and the girls ARE married
2002: Sasami is 18 she becomes tsunami.
2005- 10 years after the end of gxp- seina goes to banjo island , a 4th generation royal tree disguised space ship on earth along with Representatives from the various guilds and alan and his wife laretta. a proxy war is waged between the guilds the pirates not happy with this arrangement come to attack earth the earth officially becomes its own interstellar recognized state.
2010- 15 years after gxp, Kenshi masaki is sent to geminar. This is also close to the real life date of when war on geminar premiered. (coincidence?) sasami is 21 ryo-chan is 18. seina's first born ryo's first three and tenko and tenyeka are at least 4.
2060- "21st century" misaki and one of tenchi's sons meet and fall in love.(jurai novel)
some will say but what about all the technology in the third ova.
The technology in the 3rd ova confirms the decade
https://en.wikipedia.org/wiki/History_of_hard_disk_drives#1990s
there is a cell phone that doesn't flip and isn't smart (android wasn't even a thing when that episode was released) its said tenchi should learn to use a computer, no one in the tenchi series has cellphones except that one guy in the first episode and the girl from the opening of the first gxp which isnt fully canon anyway. there arent even flip phones so cell phones exist but aren't common yet. the computer tenchi gets is said to be state of the art. the box says terrabyte however the first terrabyte drive https://en.wikipedia.org/wiki/Hitachi_GST was released in 2007 and this episode was made in 2003. however noike and this story was written in 1993 as evidenced by one of kajishima's 1993 doujins. so its very likely someone in 2003 saw the word gigabyte and changed it to terrabyte because gigabyte drives excised since 1980 *but they were expensive* on top of that nobuyuki while messing with the computer shows that it has not only a floppy drive. but a cd drive. and a parallel ata ribbon cable. in 2003 serial ata came out and a state of the art computer in 2003 wouldn't have pata or a floppy drive. but also... if rea is pregnant when the marriage happens then kenshi gets sent to geminar in 2010 which is conveniently the a year of when it aired (but it started in 2009. but if i adjust everything down a year then 21st century no longer starts in 2060... :( ) also windows 3.1j was released in japan in 1993 to massive success which explains why they would just be getting computers. windows just became a thing.
*based on ova 3
**based on true tenchi novels
***based on gxp
~based on doujins
^*astronerd boys old timeline: http://tenchi.astronerdboy.com/section-3-1-2-additional-tenchi-muyo-items/