<ul className="nav">
    <li>
        <Link to="/section1">test1</Link>
    </li>
    <li>
        <Link to="/section2">test2</Link>
    </li>
    <li>
        <Link to="/section3">test3</Link>
    </li>
    //
    ////////////////////////////////////////
    //
    {list.map((item, index) => {
        return <li key={index}>
            <Router>
                <Link to={`/section${index + 1}`}>{item}</Link>
            </Router>
            </li>
        })}
</ul>

{this.props.children}

<Switch>
    <Route path="/section1" component={Section1}/>1
    <Route path="/section2" component={Section2}/>2
    <Route path="/section3" component={Section3}/>3
</Switch>