Early Contacts And Their Eventual Consequences

In Poul Anderson's History of Technic Civilization: 

Hermes was discovered and colonized during the Breakup;

Woden and Cynthia were discovered and contacted very early, probably during the Breakup;

Ythri, Gray, Merseia, Paradox and Starkad were discovered during the first Grand Survey - and we do not know how many Grand Surveys there were.

Later:

Hermes, Woden and Cynthia are the home planets of the three members of Nicholas van Rijn's first trade pioneer crew;

although a few Wodenites win Polesotechnic League scholarships to go off-planet, most remain primitive hunters but then Woden joins Supermetals (see below);

one Cynthian trade route joins Technic civilization early but others later join Supermetals;

Ythri and Merseia become independent interstellar powers.

David Falkayn:

is born an aristocrat on Hermes;
works on Ivanhoe, Vanessa and Ikrananka, all of which later join Supermetals;
leads van Rijn's first trade pioneer crew;
in particular, leads the crew when it saves Merseia from supernova radiation;
discovers the supermetals-rich planet, Mirkheim;
founds the multi-species Supermetals Company that mines Mirkheim;
founds a joint human-Ythrian colony on Gray, renamed Avalon;
places Avalon under the protection of Ythri.

Thus, Falkayn alone connects most of the planets and species mentioned in this post.

Also discovered during the five year mission of the first Grand Survey:

the planet where Ali Hamid of the Olga died of a poisonous bite;
the planet where an excited club-wielding being fractured Manuel Gonsalves' skull;
many unique, mysterious, beautiful and terrible worlds blurring together in the explorers' minds only because they are so many.

Read Philip Jose Farmer's remark quoted on the front cover of The Earth Book Of Stormgate. (See image.)