For those who don't understand the New Covenant and its related kingdom, the Jehovah’s Witnesses incorrectly teach that there are two kingdoms over which Christ rules. The first kingdom is called the “kingdom of the son of his love” (the New Covenant kingdom) and is a spiritual kingdom with Christ as head over the 144,000 only. This kingdom was brought into existence through the shed blood of Christ under the New Covenant God spoke of through Jeremiah at Jeremiah 31:31-34 and inaugurated at Pentecost. Only the 144,000, Christ and God are parties to the New Covenant with Christ acting as mediator for a short while.
The second kingdom, the real kingdom of God, is the “kingdom of our lord and of his Christ” (the 1914 kingdom). It began in 1914 at “the end of the “appointed times of the nations” and is over all mankind on earth” (Insight, 169; Reasoning, 95-97). The 1914 kingdom lasts forever. The 1914 kingdom, or “God’s kingdom” over which Jesus began to rule is of “greater proportions and bigger dimensions…” than the New Covenant kingdom, but Jesus received only a “subsidiary share” in the 1914 kingdom of God, they say.
http://144000.110mb.com/144000/i-2.html#IV