Timeline

The ingame content of DBNU spans much of Dragonball Z and GT with a bit of Dragonball in the mix. There is no set time period for the mobs and areas that appear and the content overlaps.

However, the Roleplaying setting is independant and takes place roughly 20 years after Dragonball GT, that is 25 years after Dragonball Z in Age 809.

This List was used for reference.

Official Timeline
Goku born
 * Age 737

Planet Vegeta destroyed by Frieza

Bulma meets Goku; the Dragonball series begins
 * Age 749

Goku kills King Piccolo
 * Age 753

Piccolo Jr born

Gohan born
 * Age 757

Raditz arrives on Earth; Dragonball Z begins
 * Age 761

Planet Namek destroyed by Frieza
 * Age 762

The Androids attack
 * Age 767

Goten born

Majin Buu awakened, defeated
 * Age 774

Pan born
 * Age 779

Goku begins training with Uub
 * Age 784

Goku is transformed into a child by the Black Star Dragonballs; Dragonball GT begins
 * Age 789

The Shadow Dragons are defeated
 * Age 790

RP Timeline

 * Age 790-809

Earth
A book released by Gohan spreads the knowledge of Ki control

In the wake of Mr. Satan's influence, Pan builds momentum for widespread interest in martial arts

Krillin establishes the New Turtle Style School of Martial Arts; Tien Shinhan establishes the New Crane Style School

Trunks and Goten establish the Kikoukenjutsu Sword School of ki-enhanced fencing

A group calling themselves the Red Ribbon Reserves have recovered one of Dr. Gero's backups and begun construction on new androids. Many androids have been recovered and reformed by Capsule Corp.

Space travel has become more commonplace with the general populace now aware of alien life in the galaxy; however, it is still rare for humans to travel offworld

The Fierians are released from the sealed cave

An unknown group has created new Golems in an effort to revive Majin Buu

Outer Space
After Planet Vegeta was restored using a wish on the Dragonballs, much of the Saiyan race was resurrected using extract from a Tree of Might.

A rebellion has begun among the Saiyans. There are those who support the revived King Vegeta as the rightful ruler, others who oppose his rule due to his failure against Frieza, and still others who abandoned their planet to enlist with the restructured Planet Trade Organization.

The Planet Trade Organization, having been destabilized by the loss of Frieza as well as King Cold and Cooler, has come under the control of Frieza's son, Kuriza.