R-CTS1751 Haplotree;

A draft CTS1751 Tree by Alex Williamson at "The Big Tree', with data from Next Generation Sequencing (NGS) at FTDNA and 1000 Genome Project;

http://www.ytree.net/DisplayTree.php?blockID=19

A draft CTS1751 Tree from YFull, with data from NGS testing. 
Age Estimates included;

https://www.yfull.com/tree/R-CTS1751/

To get the most out of your Big Y results and help us grow the R-CTS1751 Tree please consider submitting the results to;
Alex Williamson at the R-L21 Project for submission to "The Big Tree",    its free and places you on the CTS1751 Tree 
http://ytree.net/Instructions.html

and submitting your BAM files to YFull for analysis and placement on the YFull tree with age estimations. and extraction of ~300 STR values.  (Cost US $50.00,  but well worth it)

http://dnaandfamilytreeresearch.blogspot.com.au/2016/04/how-to-order-yfull-reanalysis-of-your.html

https://www.yfull.com

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CTS1751 Origins and age estimations

From FTDNA 2022;

Haplogroup R-CTS1751 represents a man who is estimated to have been born around 3,600 years ago, plus or minus 600 years.
That corresponds to about 1600 BCE with a 95% probability he was born between 2200 BCE and 1000 BCE.
He is the most recent paternal line ancestor of all members of this group.
R-CTS1751's paternal lineage branched off from R-Z39589 and the rest of mankind about 3,700 years ago, plus or minus 550 years.

There are 339 DNA test-confirmed descendants, and they have specified that their direct paternal origins are from Ireland, England, United States, and 10 other countries.
As more people test, the history of this genetic lineage might be further refined.


Age Estimate

The FamilyTreeDNA Time to Most Recent Common Ancestor (TMRCA) estimate (Beta) is calculated based on SNP and STR test results from many present-day DNA testers. The uncertainty in the molecular clock and other factors is represented in this probability plot, which shows the most likely time when the common ancestor was born amongst the other statistical possibilities.

Confidence Interval    Years Before Present     Calendar Date     
99%                           4,519 - 2,821            2497 - 799   BCE
95%                           4,204 - 3,083            2182 - 1061 BCE
68%                           3,905 - 3,337            1883 - 1315 BCE

Haplogroup R-CTS1751     Mean; 1579 BCE       95% CL; 2182 - 1061 BCE

YFull 2022;

Yfull have R-L21 as estimated to have formed ~4500 ybp, (95% CL 4800-4100 ybp)  (June 2022)

Looking at age estimation from Big Y and Full Genome test results at yFull, it appears that CTS1751 is ~4100 years old,  with a 95% confidence level of 4300-3900 years before present.  This is not that long after L21 formed,  and it is more than possible that CTS1751 formed in the same region.

See the CTS1751 tree at yFull;
https://www.yfull.com/tree/R-CTS1751/

The R-L21 project have classed L21 and his early sons as Bell Beaker Folk.
See the R-L21 Descendants Tree;
https://www.familytreedna.com/groups/r-l21/about/results
CTS1751 would appear to be in this section.

There are some who think that L21 probably arose in France/German region and spread westwards, rather quickly, eventually becoming different Celtic tribes.
Others who think that L21 arose in Britain.    http://www.academia.edu/24686284/The_phylogenealogy_of_R-L21_four_and_a_half_millennia_of_expansion_and_redistribution

From the Big Y results we have for CTS1751 we can see the main groups branching under CTS1751, which formed pretty quickly after CTS1751.  YFull have estimated formation ages for most of these groups at 4100 ybp.

BY3927

BY71093

BY54624

Z17966 BY20462

Z17966 Y18513

Z17966 Z17969 which has many branches under it including, BY3227, BY596, BY595/BY601 and BY106880.

We still have much more branching to discover under these SNPs.

The branches under these main 5 groups are obviously younger than 4100ybp. 

The more SNPs shared by 2 or more men under these main branches represent much younger and closer connections.

While the majority of our men can trace back to England, Scotland, Ireland and Wales, we also have men who trace back to Germany, France, Portugal and Ukraine.

I tend to agree with the idea that it may have originated on the Continent and that men moved in waves, over the generations, from there to Britain and Ireland. 
Some remained on the Continent, others moved to Britain. 
At the moment it's really hard to say who moved where and when.